C-2 upper manual volume problem

[justme]

If this has been covered previously, please someone direct me to the information. A friend of mine plays organ (C-2) at a local church. After being shut down for several months due to Covid, the church has started services again. When the organ was turned on, everything worked as it had been except for the upper manual volume is considerably lower than the lower manual. This condition exists, regardless of vibrato, volume or drawbar or preset settings. Looking at the schematic, the only thing that I can see that separates the upper an lower signals is the matching transformer (round can style) with "A" marked on it. Serial number on the organ is 36472. Any help would be greatly appreciated.

[muckelroy]

Clean out the vibrato select / volume switches. Also, make sure no mice have established a base of operation in and around the preset panel. Tighten all preset panel screws as well.

[enor]

All I can think off, off the top of my head, is either a short to ground in the vibrato switch assembly or a bad ground to the upper manual matching transformer.

[Drawbar Dave]

All I can think off, off the top of my head, is either a short to ground in the vibrato switch assembly or a bad ground to the upper manual matching transformer.

I had exactly this scenario in a customer's B3 this week. A good cleaning of the switch box cured it. To the OP, the signal is travelling from the matching transformer to the preamp via this switch box, so a short here would interrupt the signal.