I picked up a 1973 and 1974 MW by Gilson tractors with the Vickers hydrostat. I downloaded a manual and it states the transmission should not need service for the life of the tractor and if it leaks take it to the MW service center, HA, good luck with that. It looks like there is a plug above the filter. I suppose this is where you fill it? This Vickers has the usual leaking pintle shaft.