I recently cleaned the contacts and the scratchy volume knob, and now they great. Unfortunately the LCD glass fell out in the process. I don't understand how to put it back in securely

Try this first with the piano off, run the control from stop to stop rapidly several times. The object is to clean off any dust deposits and shine the contacts inside the pot. If the pot is not damaged beyond repair, then this should fix it.

First you need to get access to the hardware. Disconnect the speaker wires from the speaker, then unscrew the 4 screws located on the top of the cabinet (one in each corner near the corner guards). Once that is done you should be able to slide the electronics out of the cabinet. How you fix the volume knob really depends on what is wrong with it. If it is scratchy and sporadically responsive, it might just need a good cleaning, which is easy. Otherwise it might need to be replaced, which is less easy, but still easy enough if you are handy.

To clean the knob, you will need to get some electrical contact cleaner (I use Deoxit, but anything designated for this task is good...I wouldn't use WD-40). I remove the potentiometer from the face plate, but you can likely clean it without removing it if you can get at it. Set the nozzle against the tiny hole by the back of the pot and give it a quick spray, then rotate the knob back and forth a bunch of times (like 40). Voila. While you are there, clean all of the pots, as a preventative if nothing else.

If you need to replace the pot, things can get a bit trickier. If you are handy with a soldering iron, desolder the contacts on the back of the pot and replace it with the same type of pot (you can cut it out too, but that gets messy). Take note of any markings on the pot. It will likely say something like A500K...the first letter defines the type of pot (audio vs linear), and the number defines the resistance (500K, in this case). Getting the wrong pot in there can drastically change what you get out of your amp, and probably not in a good way. Solder your new pot in place, then put it all back together.

Make sure you test the amp once you have cleaned/replaced the pot before you screw everything back into place. Hook the speaker back up, power it up, and see what happens. If everything is good, lock it down. If it still isn't working, you may have a bigger issue than the pot, and you should likely take it in to a professional. Good luck!

"Overdrive Channel: high frequency noise as the gain and volume are increased."

This is the expected result, you are experiencing feedback. Try turning the "Contour" knob all the way to the left and turn down the tone knob on your guitar.

All i can suggest is to use electrical contact cleaner on it from the inside. But you,ve already done that. And i would imagine that the master volumes will be the same to, Harry

Just spray a few shots but you have to take the top cover apart, then take out 3 philips screws in the pots module, take off caps and then you should be able to give'em a good cleaning spray shots.

If the problem is actually the volume knob, then the guitar shop did not fix it and you should bring it back. There is a test you can do to see if the problem is your volume knob. With the guitar unplugged, you can turn the knob up to the max and down to the min a lot of time (like 50-100 times or more) plug it back in and see if the problem is a little bit better, if it is I would bring it back to the repair shop and demand they fix it properly.

The problem could be the cable you are using. Sometimes it can seem like it's a volume knob problem when really it's a cable issue. Jiggle the cable and connector while the guitar is plugged in to see if the sound cuts out at all or you get crackling.

try a differrent speaker of suitable wattage and ohmage (displayed with a number next to a ? symbol on the back of the speaker),

or

remove the original amp speaker and gently push in and out on it, checking for uneven resistance or scratching. the speaker should retract and return smoothly, without any scratchiness or uneven resistance from within, and if there is any of this scratchiness or uneven resistance from within, the speaker is likely damaged from too much wattage or distortion.

Try cleaning your volume potentiomenter with contact cleaner (they come in spray can's), the scratchy sound is audible when you turn your volume control on, the contacts inside your potentiometer accumulated dust or some other particles.

Here is where you can get the service manual:http://celedoniaorgan.netfirms.com/cosco/nfoscomm/catalog/product_info.php?products_id=1021&osCsid=3eaaa99d6bfceeaaf9b844687ba58d55 Since the problem is with the foot pedal note and the keyboard note I would suspect that there is a problem with the tone generation circuit for that note. You might try cleaning the key contacts on both for that note first to see if that works. The volume pedal probably just needs the volume pot cleaned with contact cleaner spray. I hope this helps. Let me know if it does.

The distorted and low volume output plus noise is usually caused by using the wrong power supply adapter. The Alesis SR-16 takes a 9V "A/C" supply not "DC". The A/C supply provides a negative voltage swing which wouldn't exist with a DC supply. So check and make sure you have 9V A/C output supply not DC.