Roland Piano 600 HP 600, out of 76 keys, Keys# 4, 9, 10,11,12,13,14,15, 23, 38, 74 will not play( no sound). Any ideas? Everything else works. Have taken no actions to fix yet.

Has it always done that? It could be it just doesn't have enough power to play organ at full volume along side the ensemble.

It sounds like there may be an issue with the piano sounds on your Kurzweil sp4-7 keyboard. One possibility is that there may be a problem with the software or firmware of the keyboard, in which case you may need to update the software or contact the manufacturer for assistance. Another possibility is that there may be a problem with the internal hardware of the keyboard, in which case you may need to have it repaired by a professional technician. In either case.

The Roland RD-600 is a digital piano, and its hammer action mechanism is designed to simulate the feel of an acoustic piano. The hammers in digital pianos like the RD-600 are typically made of materials like plastic or a combination of materials to replicate the weighted feel of acoustic piano keys.
The breaking of hammers in a digital piano is not a common issue, and it's not typically related to the age of the instrument alone. Several factors could contribute to the breakage of hammers, and it's essential to consider the following possibilities:

1. Excessive Force: If the keys are played with excessive force or if there's any physical damage to the instrument, it could lead to the breakage of hammers.
2. Material Quality: The quality of materials used in the construction of the hammers can impact their durability. If the hammers are made from subpar materials, they may be more prone to breaking.
3. Manufacturing Defects: In some cases, there could be manufacturing defects that make the hammers more susceptible to breakage.
4. Maintenance: Lack of proper maintenance, such as cleaning and regular inspection, may contribute to the wear and tear of components, including hammers.

If you've observed a pattern of hammers breaking with regularity, it might be worth investigating the specific cause. If it's due to excessive force or physical damage, adjusting playing habits and taking care during transport can help mitigate the issue.
As for whether it's worth purchasing new hammers from Roland, it depends on the extent of the damage and the overall condition of the instrument. If the RD-600 is in good condition otherwise and you enjoy playing it, replacing the hammers could be a reasonable option. However, you may want to assess the cost of replacement hammers compared to the overall value of the instrument, factoring in the cost of a used RD-600 and any potential future maintenance needs.

The key contacts have gotten dirty or worn. Most Roland keyboards use conductive rubber contacts that are pressed against circuit traces underneath the keys. These can often be cleeaned to restore operation, but this is not a DIY type project. The cost of repair probably exceeds the value sorry to say and parts may not be availablle... In this case I would probably recommend you get a newer unit as they have many decent synths now for a little over $100 and repair would likely be several times that. Also look at the used market and MANY thrift stores have units... make sure you test any for operation before buying. If one can afford $250, here is a candidate with 76 keys:
http://www.musiciansfriend.com/keyboards-midi/yamaha-ypg-235-76-key-portable-grand-piano-keyboard Also you can search Ebay but do be careful of used items that have no guarantee.

One of the lines in the keyboard scanner has opened up. I have an idea what it might be and it is a nasty problem involving circuit traces that are silver conductive paint on a plastic insulating base that separate from a jumper at each end of the strip that the key contacts are made by conductive rubber pills pressed down by the keys. The contact of the flexible circuit under the keys to the jumper cable can be broken by vibration. I have an EPS7 with the problem and other than replacing the whole contact strip under the keys it really has no easy solution.You should probably have a Roland shop look at this problem. If your unit has this same arrangement it is repairable only by replacing the whole key contact strip.

You probably need to just clean the circuit board and the conductive rubber contacts. There are two per key to facilitate reading the key velocity.

Use 99% isoprophyl alcohol and Q-Tips to clean both the board and the rubber contacts.

A rod is inserted lengthwise to hold the hammer weights while removing the boards. Use dowels from each end inserted about halfway back between the keys and the weight rods. Use a 1/4 inch dowel rod.

You have to take out a few screws to remove the boards from the key assembly. Be careful of the cables.

You either did not get the ribbon cable seated OR got it upside down.

If this cable is the flat ribbon with exposed solder plated points of contact, OFTEN those connectors have a latch to release by GENTLY moving tabs on eaither side in the direction of pulling the cable out. This lock MUST be moved out slightly to allow the cable to seat properly. The solder plated contacts will be FULLY into the connector when seated properly.

These cables ALSO can be inserted backwards and NO connection will be made.

White spirit is NOT what you should use. Mineral spirit leaves a residue film.

Use 99% isoprophyl alcohol.

ALSO inspect the contactboard for cracks by candeling with bright light behind it.

You may need to clean the contacts which are usually conductive rubber. I explained stuff for another Roland problem with two keys that were intermittent. I have an EP-7 that I had to do the cleaning of the key contacts. Use 91 or 99 % Isoprophyl alcohol to clean BOTH the conductive "pill" (Black under silicone rubber domes) AND the traces on the board where they press. Clean gently as the traces have a hard black coating.

It's not really for the faint of heart, but generally this is caused by gunk getting into the key circutry. Underlying the 3000's keyboard is a silicone pad with 2 contacts on it, the measurement between each being hit is the issue usually but yours just sounds like there's something in there causing a physical or contact obstruction.

What you really want to do is to remove the keys and clean everything but this isn't easy... You could try using 99% alcohol (from a pharmacy) to clean inside it which may well help you.

There's a good thread on a similar issue at:

http://www.electronicspoint.com/roland-hp-3000s-digital-piano-dodgy-note-t18946.html

Which may help you work out how to do the disassembly if you are brave, but I would start with pouring some alcohol in and poking it and hoping for the best 1st. It sounds crude, but it works amazingly well with some things.