It would help to know the approximate age and type of combination system which the instrument has. Clearly, from the photographs (and the fact that it possesses general pistons), it is not the original system. There appears to be a setter piston, so the piston action is probably on a type of 'capture' system. I note that there is at least one hinged flap, at the treble end of the console, below the stop-key sweep. This may not be original, and it may house a multi-channel selector unit.
However, without knowing the answers to the above questions (and without examining the instrument), all we can do here is offer general suggestions - such as on no account should WD40 (or any other substance) be introduced into the workings of either the instrument or console.
Again, I would guess that the piston system was installed (or at least upgraded or even renewed), perhaps either at the time of the 1988 or the 2002 tonal alterations and additions. However, the NPOR survey makes no mention of any alteration to the action or piston system at any time.
It is possible that there is a problem with the console rectifier(s), and that there is a voltage drop. It is also possible that, for some reason, the piston system has developed a fault. It is also possible (but less likely, if my conjecture regarding the age of the system is near the mark) that the piston action is, for whatever reason, nearing the end of its useful life. This can depend on a host of factors: for example, type and quality of components (not least the wiring), quality of original installation, presence of dust, damp or other environmental issues, interference by unqualified persons, amount of use it receives and several other considerations.
However, whilst it appears clear from your original post that you wish to save your church money, I would caution that attempting unskilled do-it-yourself repairs on any part of the action of an organ (particularly where electrical components are involved) may, in the long term, cost the church considerably more money. There are many cases of this type of thing happening and a church having to spend a considerable sum of money, in order for a qualified organ builder to repair something which, however well-meaning, has been bodged.