I puzzled until my puzzler was sore about how to affix a torque arm to the NWSL 28:1 gearbox. #10 taught me that we want the arm to be as beefy as possible. But these little 4-4-0s don’t allow us to be profligate with space. In particular, there is no extra space on top of the motor; there is space on the side because it’s a flat can, but the gear box bulges inconveniently on the side.
In the end, I fashioned an L-shaped bracket that screws to the front of the gearbox. It has a small 45-degree angle in the corner to provide room for the motor contacts and wires. The contacts sticking down from the end of the motor are quite inconvenient, and wouldn’t fit at all in the boiler barrel.
Following Don Ball’s suggestion, I ran the motor while the the silicone set. For some reason, even with that good advice, it is slightly happier with a small shim to hold the motor 1/2 mm away from the gearbox.