Hi

To stop the HL Jerk you can use one of the Platine ARM-02 für RX14/RX18 from TankModelbau - link below. I have used one in my STUG III and also Jagdpanther prior to starting work to convert it to a TAM DMD unit. Works a treat and as a company they are excellent to deal with.

[link]http://www.tank-modellbau.de/[/link]

Hope this helps

cheers
Gorehound