Update on the Heljan Class 16 saga........
Pick ups/wheels etc checked and loco given time to run in. No change.
Each bogie/gearbox was stripped, any white grease removed and all then re-assembled with light oiling. Everything rotated freely. No change to the running.
Each bogie was then stripped and rolled about the place. Initially checked without worm gear in place. Free rotation but some expected slight resistance. Removal of gears and everything ran freely when gently pushed.
Re-assembled and each bogie was re-connected to the motor in turn. That is to say the loco was run with only one bogie connected at a time to the motor, then disconnected and the other bogie connected. No change.
Both bogies disconnected and the motor observed. It was somewhat sticky at low rpm with uneven rotation to start. One direction noticibly tighter at low rpm than the other.
Light oil was applied on the bearings and left to run on medium power but disconnected from the bogies for about 2hrs each direction.
Bogie reconnected. Smoother bonnet forwards but working cab first very uneven at low rpm smoothing out as the power was applied.
Conclusion.............
Replace motor. Problem is removing and replacing the flywheel/ integral plastic UJ assembly on the new motor......once I work out if I need a 43 or 48mm example or even a non-Heljan alternative if I can find a cylindrical equivalent with correct size shafts.
Only Heljan motors I've found online thus far are sans flywheels.
Gaugemaster ( spares distributor) show no spares for this model (or the Class 15 incidentally).
So it seems any replacing of the motor, either by way of a Heljan motor or otherwise has the same issues re flywheels etc.
The Mashima 1626 seems a good replacement but it has 2mm shafts and would need the flywheels opening up to accept, which I don't see as a drama, just time consuming.
The top speed of the loco is not a concern as my layouts are small, shunty types. It just needs to be smooth, slow and creepy.
Definitely worth doing but a post Christmas job methinks.........
Rob.