Hello, Well I purchased several GS-4's when they first were available. Then came the replacement drivers with the metal axles to replace the plastic axles. Currently, the locomotives run fine, am I tempting fate by replacing the drivers with the metal axle replacements? In addition to that, I am not a steam mechanic, I can handle most diesel locomotives, but I have never disassembled a steam locomotive. Perhaps there is an expert on here with the skills that might like a little side money for their efforts? Or do I leave well enough alone and worry about the metal drivers when there is an absolute need? Insanity either way?