I've also recently discovered that there are lots of intermittent grounds between the RCA chassis jacks and the chassis itself. Again, years of oxidation and a relatively loose riveted fit holding the jacks against the surface of the chassis. If any one of these junctions has high resistance, your reverb is dead! I actually had to run a special grounding bus to every single RCA jack in my '72 Sceptre to get the reverb working and now it's fine.
Good luck!
I had the same problem getting the footswitch jacks to work on my '69 Sceptre. I don't have a FS yet, but I was testing the jacks with a pair of phono cords from my stereo, shorting out the tips w/a jumper: no change in the tremelo. Running the jumper from the hot contact to the chassis did the trick, ergo the jacks weren't grounded properly. There was a lot of cursing & sweating went into the repair work, slaving over a hot soldering pen, but it's ready for me to build my own switchbox now (tracked a couple of genuine Sunn F/S's on Ebay recently, when the bidding exceeded $50 I walked away...one went for a C-note when the smoke cleared
)
Haven't really researched why the 'verb doesn't work yet, but I'm guessing the problem lies in the phono plugs/jacks somewhere. Still deciding if I want to fix the reverb, or get me a "half-fast" delay stompbox...
