I have a A-B-C EMD f3 units from Precision Craft Models ( Old BLI). I have lost the sound with LOK decoders. I have been frustrated trying to find replacement decoders. Last night I tore them down and did some diagnostics. The decoders operate fine for my use but I really miss their sound. I found that when I took the shells off and flip the speakers up that this is where I found this issue. I put them on the track and pushed on the speaker material and the sound came back as long as I held pressure on the speaker. There are 4 speakers total and 3 of them are bad. They just get dry I guess and I was about to spend a small fortune on new sound decoders. Now the new speakers will cost me around $32.00 shipped from Micro-Mark. Lesson learned not to assume what is wrong until you do a little Diag. work.