Mornin.
Here should be brief, edited resume of what I did to 2 of these. This applies to the first issue and I posted it on another forum which was active on this topic at the time. Hope it is if some use.
Steve
I've just re-motored two of these for a friend with Mashima Flat Can 16/28s. ?? 20.50 each inc p+p from CometModels.This gives you as much quality motor as you can get in very easily.
The flywheel bores need opening out to 2mm, and there's a small locating pip which needs removing from the chassis casting. The top plastic half of the motor mounting clasp can still be used by careful use of the 4 screws, run only partway in.
The other problem which occurs with this model can be tightness of the gear tower assembly.
I removed the brass worm and its attendant bearings,note the flats filed on the top edge to stop the bearings from spinning,( there was no end-float between these three parts, and the stub axles were a little too snug in the bearing bores).
The inner faces of the bearings were dressed back a little and the bores opened out likewise.
Both are now re-assembled and running in lovely. Dead slow crawl at 1v, whereas the motors supplied wouldn't even run with no load at less than 6v and sounded like an angry wasp.
Shouldn't be necessary, of course and I' m glad I didn't wait all that time for them to appear with these faults. Poor assembly coupled with an awful motor! That said, it's a nice looking model but runs like a dog, unless you've been VERY lucky.
Steve