Everyone here seems to have praised the running qualities of this Dapol Terrier, so I went ahead and purchased a BR black one for my test track / experimental 7mm lab and was sadly disappointed. Slow speed running was very poor, current pick up was intermittent, and "running-in" (such as I could manage) seemed to make things worse, not better. Now, I am sure that I was unlucky and I just had a Friday Afternoon lemon, but just in case anyone else has had trouble here is what I did -
The design of the motor/chassis etc seems fine, it was the very poor assembly which turned out to be the problem. To rectify this I removed the body from the chassis after taking out the outermost four screws on the underside. The body is quite a tight fit, so you have to very gently ease it off and also remove the glowing fire pcb which is held in with double-sided tape. Mine turned out to have two basic problems - first, the engine was making a strange ticking noise in both directions at low speed. If you have this problem, don't ignore it, it is caused by dry motor bearings and a slightly eccentric flywheel. I lubed the bearings at both ends of the motor using Singer oil and an oiling pin, it's tight in there but you can just do it with care. The second problem was that the wheel pickups (which are springy copper strips) were not tensioned correctly on four of the wheels and were losing contact altogether at times. You can check for this by holding the mech upside down and pushing the wheelsets sideways to make sure that the pickup stays connected with the back of the wheel. I removed the brake gear assembly (which plugs into its sockets and is not glued thank heaven) using a pair of needle-nose pliers with the jaws softened with masking tape. Then you can undo the remaining screws, take off the baseplate and drop the wheelsets out. Very carefully and gently bend the pickups out from the frames until they spring nicely against the backs of the wheels. Then clean the treads, backs of the wheels and pickups with alcohol or similar, reassemble everything and lube all the moving parts with LocoLube synthetic. After all this my little Terrier runs sweetly down to a crawl, as she should!
Have a great Christmas!