Hello and welcome, Tbird
The manual and schematics for Randall’s RG80 can be had for twenty bucks from this website:
http://www.musicparts.com/products.asp?Company=Randall
but, in my op, I’d wait a while (I suggest about 60 years) before taking advantage of this offer. I went to Randall’s own website and took a look at their downloadable (free) manuals. This is the URL:
http://www.randallamplifiers.com/about/warranty/index.asp
and, as you’ll see, there is no mention of the RG80. However, a click on the RG100 brought up this pretty thin “.pdf” document:
http://www.randallamplifiers.com/about/warranty/manuals/rg100scmanual.pdf
Imagine if you’d spunked $20 only to get a similar, two-page, blink and you’d miss it document. If the RG100 details are no use to you, try the Randall forum:
http://www.randallamplifiers.com/Forum/index.asp
register, and ask if you can get a copy. Chances are that a Randall-employed mod will reply and sort you out. Failing that, another user should.
As to the footswitch, again, you can try the Randall site:
http://www.randallamplifiers.com/accessories/footswitch.asp
but my guess (only a guess at the moment) is that you need a simple, latching (on/on) footswitch. Without a nice “Randall” logo, and made in China somewhere, these are now almost literally a dime a dozen. Come back here if you need more info and/or can provide more details.