I wanted a couple of such servos for a current build and after looking at the price (£14) and anyway was bigger than I needed, I had a look though Mayhem's pages, and yes several threads on the subject, so decided to make my own. I took a few pictures of the hack for which I claim no invention but just share them here for anyone else who wants a similar, low power and importantly-cheap!! item, especially if you buy several at once for about £4 each. It took less than 10 minutes for this clumpy fingered old man to do two of them and so is within anyone's capabilities.
1/. Open up the case and remove idler gears,
2/. pull the final drive gear off the pot shaft, trim off the 'limit' lug that projects under the gear and drill the gear to be free on the shaft
3/. power up the Tx, set all trims to neutral, power up Rx and plug servo into one of the stick ports, the servo motor will probably run, slowly turn the pot shaft till it stops. Twiddle the sticks a few times to get it running both ways and to ensure that at neutral the motor stops.
4/.without moving the pot at all, apply a small dab of cyano to the wiper, allow to set, then reassemble the servo.
You'll now have a servo that can be variable speed, constant rotation or start and stop in either direction depending on whether you use a centring or non self-centring stick or its trim lever to make it move.
Trevor