Reviving the Haig - Part 2

Today I decided to investigate the running problem. The chassis seemed to run OK out of the chassis, but when I put it under load (holding it back) the worm started slipping on the gear. On closer inspection I realised the motor (and mount was twisting to the side, and could slip off the gear. After a little thought, I moved the motor over with another piece of 1mm plastic to the side of it. I also superglued the brass strip to the plastic packing beneath it, which is a tight fit between the "springs" on the tops of the frames so should help to prevent twist, and having noticed if the bolt was tightened too much there was a short, I stuck Sellotape on the underside of the brass as I suspect it can touch the springs. 

That improved things slightly and the loco ran up and down OK, but again if run under load the motor started slipping. This time I noticed that the motor could lift off the brass mounting plate. It's stuck with contact adhesive which remains a little rubbery, and it may not be helped by the motor which does run quite warm, so allowing just enough "give" for the gear to slip. 

After some more thought I figured the motor needed to be physically held down, and decided the easiest way was with a wire that could be tensioned. I drilled a hole in the brass each side of the motor and looped a wire through, twisting the ends together. I tried a copper wire but it snapped, then found a steel wire in my useful-wire-bits tin which could handle the strain, the ends were twisted with pliers until the motor was held down tightly. Of course the wire over the motor required some of the lead in the boiler to be ground away for the body to sit flat, and the twisted end needed to bent over and tucked carefully into the body when fitting the chassis, but it seems to work.

Running is still not quite as smooth as I'd like, there's a little hesitation at times and it can be prone to the odd stall which is odd given the 6-wheel pick-up all seems to work fine and I can't feel any binding in the chassis, although after a little more lubrication and when warmed up it seems acceptable. Perhaps a flywheel will help if I can find one to fit (needs to be 10mm diameter, 3mm deep, and 1.5mm shaft).