Try a mixture of mineral spirits and a bit of Isopropyl alcohol (97%). I heard that works on silicone caulk used to make fishtanks.

Analog heaven sells the fatar keybeds for 40 bucks. Follow the link i gave you.

Do the acetone wash before you buy chips.

What is your budget? If money is not an issue i suggest your get an Alesis Andromeda. It really is the best analog synth around.

Make sure that the CV input connector is working right. Use a voltmeter to test for control voltages. If the CV voltages are fine, it might be something wrong with the track and hold amplifier.

Could also be that the volume pot is scratchy.

NO PARTING OUT!! Please don't destroy synths to make a couple of bucks, simply resell to someone who is qualified to repair it.

You can buy new keybeds here:

http://www.analoguehaven.com/doepfer/mke/

If you can fix a juno60 go for it! If you plan on sending it out to a tech first find out exactly what is wrong with it.

You probably have a busted opamp or something like that. Does it have aux outs you can test?

If the battery where dead then your patches would not stay in memory either.

I really recommend talking to roland yourself. A lot of "Service Techs" have no idea what they are doing and will "fix" things by simply swapping out entire boards as opposed to troubleshooting and replacing parts. It would help if you posted a link to the service manual.

Try finding a service manual, this will give you a better idea of what to do next. I really don't think spending $500 to fix it is a good idea. You can probably buy a whole other synth with that much.

Definately a loose ribbon cable, or perhaps a bad solder-joint/broken trace somewhere. I recommend NOT smacking the poor synth as a means of getting rid of the problem.

Most likely what happened is the EEPROMs that hold the operating system are corrupted. To fix it you need to reload them with the proper OS. Dont know much about the JP-8000 but if you are lucky the EEPROMS are not soldered down and you can remove them and load the OS using an EEPROM programmer.