It plays for about 30 minutes and then just stops, as if overheating. After a cooldown period, it starts up again for another short period. Suggestions? Any recommended vents I could cut in it? Tia. Norm

sounds like bad caps and maybe a failing output transistors. Use Deoxit contact cleaner too.

Probably a component in the power supply is overheating, You need to take it to the repair shop.

check your pickups and the cord going to the guitar..for shorts..

Sounds like a resister is bad..

After the volume drops off, let the unit sit idle for a minute and then try it again. If the volume has restored for another brief period, suspect the filter caps are weak and voltage drops when you start driving the unit. In any case you need to have it serviced. Unless you can see the heater in a tube going out with vibration this may not be a DIY repair. If you see purple glow in a tube, replace it.

Instead of waiting a day, cool the thing down as quickly as you can and try it to see if it is a therma; problem.

You MAY be driving it too hard and the amp chip is going into thermal shutdown... This is a small amp and not intended for major loud use.

TRY playing softer and see if it lasts longer before failing. If you are overheating the internal chip because you want it loud, best to get a bigger amp...

Next test is to turn it on but DON'T play for a time period of more than the usual few songs and then see if it is already dead or you have to play awhile before it fails.

You may have a switch that may be bad. For the sound level high and low may need new tubes or possibly may not be seated fully into position. These tubes due get quite hot and do get loose over a period of time.Hope this helps.

You don't tell us the model, but most have a "demo" button which is first pressed and then there sometimes is a start and stop button tto control it.

DO NOT use while this problem exists as you may damage your speakers.

You may be overheating the unit and the thermal cutouts may be opening... CHECK that the fans and vents are all in good order.

Check that you are not putting speaker loads LOWER than the rating of the amp onto the amp.

Our bassplayer had the same problem with his mb4410. As it turned out, the fan was not working when the amp got hot. It did turn when cold - go figure! Swap the fan for a good quality (Pabst, Sunon) 80mm pc fan with 2-wire connection. Three or four wire fans will not work w/out modding. See your local pc guy and ask for an unregulated, silent 24/7 fans. He will know. Our bassplayer sold the P.O.S. while still in warranty. HTH.