Fender Frontman 212R reverb

[philly]

Hi All,
Looking at a reverb problem for a friend and just need confirmation before I go an order up a reverb tank.
Problem -- No reverb at all. All tank connections, springs etc checked and ok. If I shake the tank I here nothing on the speakers. If I inject a signal on the return signal from the tank I can hear the injected signal. If I inject a tone on the tank input I hear zero.
All other functions of the amp seem to be working normally. I have replaced both ic's U4,5 in the reverb circuit as I had them in stock and the amp stripped down anyway.
Looks like the tank or am I approaching this correctly.

[J M Fahey]

Start by measuring reverb rank coils DC resistance at both ends.
I would expect in the order of 50-100 ohms at the output and 5-20 ohms at the inputy.
That would be DC resistance, impedance is some 10X higher. 

IF one is open, look inside, often thin connecting wires break , the spring cradle itself is spring mounted and shakes a lot.

[g1]

Schematic attached.
In the unlikely event that the tank turns out to be ok, make sure D15 at tank input is not shorted.