I am having an issue with my 3 Point Hitch drifting down on my BX1850. I have messed with the speed control knob, and even when closed it still drifts down (without pressing the down lever of course). Was moving some trailers in the yard, and it drifts down pretty quickly. I fear that it might be seals inside the unit, but am starting here to see what you guys recommend for testing / troubleshooting before I jump the gun.