Improve RD-50 Reverb?

Recently acquired a very clean RD-50 head, dates from 12/83.  Has the Mid Shift toggle in place of the Clean/Limiter of the earlier models.  All original caps, no signs of leaking, and the amp is super quiet at idle.  Sounds great with no extraneous noises.

Reverb was dead on it, tank was shot.  Correct replacment (MOD brand) connected, Reverb now works, sounds good but not strong. 

Cable between chassis and tank checks out fine, as do the components (resistors and caps) and grounds around IC-3.  Swapped in a different IC-3 opamp, helped quite a bit. However, set to 10 (full up) Reverb is where I'd expect it to be at about a setting of 5.  Below 5 Reverb is barely audible, at 3 it is gone.

Plan to do a full recap, until then is there anything else to check/replace to make the Reverb stronger?