With the reverb tube testing well on a tube tester, I removed the reverb tank from the bottom of the cabinet and saw one of the springs had come unhooked from the transducer magnet. After re-attaching it, I checked the DC resistance of both transducer coils. They both looked normal so I returned the tank to the cabinet.
The reverb was still out after the tank was returned so I removed the chassis to have a closer look. Here is a shot of the inside. you can see the date stamp of September 10, 1971.
Before I did anything else to the amp, I removed the death cap and disconnected the ground switch. I also re-routed the hot side of the AC line through the fuse and switch and connected the neutral straight to the transformer. This is how modern Fenders are wired because it's safer for the amp and the person playing through it.
Here's another shot of the board. The owner wanted to keep it as original as possible so I didn't change out any electrolytics. I checked the plate and grid resistors on the power tubes out of curiosity and found them to be spot on. This amp was probably not played very often or there would most likely be some measurable drift.
The reverb transformer tested open on the tube side so I removed it and found a modern replacement.
To maintain the original look, I switched out the metal jacket from the old transformer and used it to cover the new one.
New and old
Here's the new transformer with the old jacket ready to be installed. Other than the wire, it looks convincing.
Back on the chassis
Soldered in the circuit
At this point, the reverb sounded great. I noticed that the foot switch didn't have any effect though.
The wire had become disconnected from the RCA plug so I decided to cut and re-solder both the tremolo and reverb to keep them the same length.
Removing the shielding
Removing the rest of the wire
Good as new
I really enjoyed testing this amp out after the work was done. The caps are bound to fail eventually but right now it sounds killer.