Noisy motor-older HO B30-7 diesel

[JEL1948]

I have recently installed a Digitrax sound decoder in an older Bachmann Plus B30-7 diesel loco. The motor makes a clicking sound that almost covers the decoder sound. The sound reminds me of the old 'cards in the spokes' noisemaker we used to do to our bikes. Anyone have experience with this issue?
I am considering a new motor!
Thanks