I cannot find a service manual online for a Super Reverb Reissue. I want to take a look at the foot switch jack, but I can't figure out how the box with the electronics is removed from the amp.

Would anyone care to walk me through the process?

Thanks for any replies.
The electronics are all housed in the chassis, which is a metal box open on the top. The chassis sits inside the headshell, which is the wooden enclosure with the tolex on it. You can unscrew the chassis and pull it completely out of the headshell, exposing all of the inner workings. I hope I don't have to tell you to have the amp unplugged for this. Better still, leave it unplugged for a few hours first, the filter caps hold a charge for a long time.

There should be four large screws on the top of the amp (not including the ones on the handle, don't undo those). On Fenders they usually have a plate in between them. Unscrewing those will release the chassis. Be careful, you don't want the chassis to fall out. You'll want to have your hand under it when you're taking the screws out. Hold it by the corners or the flat part, not the transformers.

Here's what the chassis looks like:

After you have the chassis out, I cannot stress this enough, do not poke around in it unless you are very sure of what you are doing. The footswitch jack is harmless, but there are plenty of other things in there that are connected to the filter caps, which can hold a lethal charge for a long time, even after you've unplugged the amp from the wall.
Thank you for the reply, Roc8995.

I haven't yet gone back to try to remove the chassis. I looked last night, and I saw two screws in the lip of the chassis at the rear. I didn't see any other screws that looked like they held the chassis on. Those looked like they held tube sockets and other parts in place.

The screws on top of the amp, other than for the handle, are the four that hold the two chrome trim pieces in place. I don't think those are what you're referring to, but I'll give them a try.

As for touching the filter caps, not to worry. I have a lot of experience with big capacitors, and have a lot of respect for what they can do.
Those chrome trim pieces are to keep the screws from ripping through. You will need to remove them.

I really do not think you should be attempting this though. If you can not figure out how to open the amp up you have no business poking in the inside

Take it to a pro
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
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Krank 1980 Jr 20watt
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Too late. I already fixed it.

I've done ground-up restorations on show cars, fixed TV's, welded, run wiring circuits at work and home, and a lot more. I just couldn't see anything that screamed "remove me to get to internals".