Woodsy
I do not have an answer to your problem of fixing whistles and bell in coal tenders. You probably will not follow my cure for train whistles and horns, as it is not for everyone but I did make my train running life much easier by doing the following:
I installed a junker Lionel steam whistle in a building with open windows on the original train board and I installed a Bachmann HO Shell Oil Storage Tank that has a diesel horn in it on original train board. Real Oil Storage Tanks come in lots of sizes. I added another junker Lionel whistle and diesel horn on the new addition when built. I put a button to operate each on each end of the both control panels each near the Lionel LW train control transformer for easy access. Both control panels have buttons for horns and whistles on both boards. This allows me to have whistles and diesel horns no matter which engine or coal tender is on the train board.
I find the Lionel whistle is much more reliable in a building because it does not have a middle rail pick up and a DC relay like when in a coal tender. They do not require train transformer power and good transformer diodes for DC voltage. It is just wired 14 vac directly to the whistle motor.
Many of the Diesels that have horns (F3, etc.) that require batteries. I hate batteries in trains as they will leak and usually have expired when I get around to operating them. I have too many engines to bother with batteries including the newer ones that are required for electronics.
The layout transformers do not have to have a working whistle or horn button meaning I do not have to maintain the diodes in the transformers to made DC. None of them work on my 3 LW transformers and I do not care.
Most can not tell where the train whistle or horn sound is coming from on medium size layout.
Today I often buy locomotives without the coal tenders and coal tenders without whistles, often at a much lower price. Whistling coal tenders also are heavy dead weight (not on the engine drive wheels), waste amps, and slow down the trains. Only one or two of my diesels has a horn installed.
Just an idea to consider
Charlie
