Its the safety cab (W version) which is a nice piece.  Being a Spectrum engine, the detail is very good and the unit is good enough to save if possible.  I hope the unit can be repaired.  I'll hear something in a few weeks and hope for the best.

Thanks for the suggestion.  The specific engine had that coupling slipping which was probably worth trying to repair myself.  It also had another issue with the driveshaft slipping above the truck joint (different drive issue on each end of the unit) which created another chance to try a different repair solution.  Having two repairs of different origin and type, and no clear solution on the other driveshaft to truck joint repair (parts didn't match my unit), I was between a rock and a hard place.  It may cost more to have Bachmann repair.  I guess I may have jumped the gun on options for repair before sending it to them.  Probably could have been done with a minimal of parts even if it took a few shots at making it work.  Bachmann Service received the unit on the 10th of February and gave me a 4-6 week response time.  Since it wasn't weathered or customized yet, I didn't risk not getting it back from service with all the extra time wasted (replacement option).  Only time will tell on the outcome of what Bachmann can do in their service department.

Thanks for the note.  That was what it looked like to me.  I have a Blue Box Athearn Dash 8 40CW as well and the drive looks identical.  The parts on the Bachmann website didn't match the parts in the Bachmann loco which makes it confusing.  I chose to send it to Bachmann for an evaluation and will take the repair or replacement when they look into it.  The motor cost with the drives was an option but the cost was going to be more than the flat rate cost at Bachmann service.  I'm not married to the unit as it wasn't customized or had sentimental value, so offering it up for repair or replacement seemed logical.

You were the second person to mention loctite as an optional fix.  Looking closely at the unit, I think the drives would last a little a couple of hours and then be back in the same condition.  Good running engines, rolling stock and track is the goal of model railroading in my book.  Putting bandaids on them goes against that philosophy.

Thanks for the advise.  I considered doing that until I found the rear drive had a different issue.  It was still intermittent drive, but caused by the motor to drive shaft not engaging all the time.  Before I spend $30 in parts and shipping, it seemed more appropriate to spend the $35 with Bachmann and get everything fixed versus taking a chance.  Love working on them but know when its time to punt.  That wouldn't be the case with another manufacturer but since Bachmann stands behind their units like they do, I think exercising that options is the right way to go.  Worst case is I'll spend another few bucks but get back a fully functioning loco.

After talking with Bachmann directly, they recommended that exact path.  I've completed a repair order and getting ready to send the unit back for evaluation.  The model is not currently in production so if they cannot repair, it will probably be a similar (not exact) swap out.  Glad to hear your suggestion was exactly what I thought and Bachmann recommended.  Its great when all signals point in the same direction.  Thanks for the suggestion and note to be patient after the holiday surge.

I have an older Bachmann Spectrum CSX Dash 8 which has some drive issues.  The motor runs well but the transmission of the power to the front and rear drive trucks is intermittent.  It appears that the drive shafts or connections of the drive shafts are not engaging with the truck drives.  The truck assemblies seem to run free separately.  Any clues as to what parts to replace or if it the best bet is to send to Bachmann service for repair.  Don't want to dig into the unit if it is better to just use the lifetime warranty for Bachmann loco's for their drive units.