My clean sound is very dirty. it sounds like the crunch channel is on and turned down.

The VT 60 was made in the USA and was a very good sounding amp introduced by SLM (St. Louis Music) in 1989.
There are three channels: clean, crunch and overdrive.
You should be able to obtain a decent dirty using crunch channel but if I remember well you MUST have the dedicated pedal to switch channels and reverb.

check out your input grounds on your amp

Buy a Double Volumn Pedal !

have you tried using a foot pedal? Are you sure it is switching (green light turns red, etc?). On the lead channel are you turning up the gain all the way and the volume down?

Microphonic tubes can be detected by tapping them lightly with a pencil. I cannot find if this uses a spring reverb, but if it does, vibrating the cabinet will get a clanky type sound from the reverb tank. This MAY use a digital reverb however which is immune to that. Next thing is to make sure your guitar can't "hear" the output sound of the amp because the strings can pick up the sound and resonate feeding back into the amp. You can detect if this is happening by quickly dampening the strings and see if ringing gooes away. You probably need 6 to 10 feet of clearance between the guitar and the amp OR put your body between the amp and the guitar. ALWAYS set sound level at safe levels. Get a sound meter and go no higher than 90 Db. I know a lot of near deaf musicians whose careers are near over because of hearing loss using too high level.

Typically ONLY one effect will be active at a time unless there is a specific mixed effect available. The gain levels between the different effects are often not too consistent. In summation, this is probably the nature of the beast.

Look for bad electrolytic caps in the bypass caps for the power to the preamp stages.

There are 2 channels, Which means there are 2 sets of knobs ... One for clean and one for crunch. Start out with a low master volume and set up the crunch, Then the clen and switch between the 2 and make adjustments until they match volume wise ... Then turn the master up.

If you are using the factory settings, and you have accidently changed the settings. Look at your manual and it tells you how to get it back to factory settings. If you tweaked the clean channel when you got it, you will have to play around with the settings to get what you want. Hope this is helpful.