DOD FX60 issue!

[WorkBench]

I just found this old DOD FX60 Chorus pedal in an old barn my brother recently purchased.  Anyway, the pedal works, and sounds decent!  The only real problem is that there is a lot of hiss when the effect is engaged.  Does anybody know anything I can do to fix that problem?  Thanks!
Chris

[cd]

You can place caps in the circuit to kill the high end (and the hiss) but that's just the way the circuit is.