I had the same issue with a 220 voyager running slowly. I tried the brush spring fix but this made no difference so I then took the gear towers apart to find them full of horrible grease so I cleaned them out, applied a drop of oil and reassembled. It now runs a lot better, faster and smoother (dcc hardwired using a lenz standard chip. Was going to get a new motor so glad I didn't now, but they can be obtained from Bachmann spares dept for £25. Now need to get the lights working!