Decoder/motor for Peter Witt Trolley

[jscola30]

Hello all, a while back I purchased a Peter Witt Trolley. I do not at the current moment have DCC, so I operated on standard DC. I began to notice after periods of operation the unit slowing down, but returning to normal after being stopped. One day, it stopped for good and Bachmann graciously replaced it. In getting the replaced one, (and also another Peter Witt and a mogul, both of which are great) and learning more about DCC, I run them VERY SLOWLY at low power, basically as soon as the wheels turn, that's it. Everythings been fine, but the other day, the replaced Peter Witt, the wheels didn't turn right away, so I opened the throttle a bit more and it finally moved, but then I realized it might be moving too fast, and sure enough it stopped, lights still on though. So, did I burn another decoder out? If so, would replacing this be enough? https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=70_640&products_id=7830&zenid=vgi25i4maqifg6n9ilc0okcu40 If so, how does one do it? I do intend on getting a DCC system in the near future.