Okay, so during the silverface era, CBS decided to beat the living hell out of the reverb driver, lowering the cathode bias resistor to 470R. Easy fix here, just replace the cathode bias resistor with the blackface value of 2k2 bypassed with a 25uF cap.
Another nifty trick is to replace the reverb driver's grid leak with a pot, aka a dwell control. That's how it was labeled on the original reverb units, though it's a little disingenuous as it doesn't control how long it takes for the reverb to decay (I mean, how could it, right?) but instead it controls the level of signal sent to the driver, with the existing reverb pot controlling the level of signal coming off the recovery gain stage. With a dwell pot, you can dial in a much more subtle reverb sound that's more dynamic.
I just put the dwell pot in the place of the humdinger which had fried ages ago due to a heater-to-plate short. While I'd like a proper humdinger, a pair of 100R resistors off the pilot light is better than a blown pot!