1975 Fender Pro Reverb P/P Master w/5AR4 - Schematic?

[Jecarroll7]

Someone added diodes on the rectifier socket of a'75 Pro Reverb amp. At least it looks like a mod as they are not on the schematic. Tube map calls for a 5AR4 which is what is in it.

Visually, it looks like the Iso trans may have gotten very hot at one time. Something leaked out a while back. Plays okay but seems underpowered to me. Haven't dug any deeper yet, was curious about the diode additions if anyone has any insight?

[Jazz P Bass]

The diodes are there to help 'protect' the amp if the 5AR4 goes bad.
http://music-electronics-forum.com/t24812/