Hi... Yes MTH has a huge problem with protosounds and the battery going. If the engine has sat around for a while and the battery goes bad, if you try to run the engine sometimes the ciruit blows and you have to replace the board.
Unfortunately we don't have the time to test and change batteries so we sell all items with protosound as is.
It is very much recommended though before operating any mth item that has protosounds that you change the battery with a new fresh one. The chances of the protosound working are good if that is done.
This is sort of similar to Lionel post war F3 horns. Most do not work and that is a given with most knowledgeable collectors. It's ironic that something similar happened with MTH engines.
