MST-202-555A peerless transaxle stiff shifting from neutral?

shift here is a euphemism. I'm pretty sure, despite the fact that MST stands for "manually shifted transmission" that this is a hydrostatic drive. You don't use the clutch to shift and it has one reverse speed and two forward that are really more like ranges on a Murray 46" lawn tractor.

I have two other Murray hyrdostatics that shift from the pedal. you push the pedal forward to go forward and backward for reverse.

The 'shifting' lever on this MST via a linkage turns a rod (maybe 5/8" diameter) entering the top of the transmission near the oil fill. Don't know if this is supposed to move gears relative to one another, or is a valve directing hydraulic flow. The Tecumseh manual doesn't even show this entry, any seal or anything to do with it so I'm kind of in the dark.

This operation of twisting the rod via linkage has become very sticky and most of the time the tractor will not go into reverse (linkage just flexes rather than completing the extent of twist require to reach reverse.).

It is tough but not impossible to put in forward ranges although sometimes it won't go into high.

I haven't dismember the linkage and tried shifting with a pipe wrench or vise grips yet. thought i would post the symptoms to see if this is reconizable ailment.

Never seen any serious leakage of fluid from the transmission although there is evidence of a tiny bit of passage at the seal on the brake side of the transmission.

The Peerless Manual has an MST 200 style which is pretty similar. Manual calls for 90 wt. gear oil which stuck me as heavy for a hydrostatic, but i defer to anyone who knows about these trannies.

You are supposed to use some special tool "Dipstick 39542" after pulling rubber plug for checking level of gear oil. Can anyone offer substitute method for approximating fill level. Could low oil lead to the kind of symptom I'm experiencing in anyone's experience. If I was really low, I'd think I would be experience drive trouble -- which I am not, only 'shifting' trouble.

Thanks,

Brian