i have one in my shed ready to gut out the internals once the one of my zs180 starts rattling.

when i bought mine 3 years ago and it was rattling so i took the VIS motors off and resoldered up the internal joints - tested they work with a borrowed tester off a member on the MG-Rover.org (LOWEdb i think his user id was) and its been fine ever since.

a member on the rover 75 forum (stocktake) has developed a self test vis motor, which is neat! Have you checked its not just the motors causing your issue rather than the location pegs?

i have researched this quite a bit and i have a report from land rover stating that the oil mist in the inlet manifold is not an issue, but they did not state what the cause was of it failing? typical!

I have not ran a catchment tank/filter and the jury is out on whether it actually helps, personal choice.

the variable inlet tract lengths that this system employs, only induces a minor torque increase at certain revs of the engine and for all the hassle and cost of replacing i'm just going to gut it. Then i wont have the worry of pieces of plastic getting into the engine either.

also on the mg-rover.org website there was 'sheddist' developing a metal and pin version but i have not seen any movement on it for years now but he may do at some point.