Sticking RL02 positioner

[Charles]

One of my RL02 drives (that sat for a long time) has developed what appears 
to be a sticky head positioner.
But it's only a problem going from the full-retracted position to loading 
track 0.
Once it's loaded, the drive will pass all seek and read/write tests.

It takes a surprising (to me) amount of force to pull the heads out into the 
disk area (power off, no pack). When they're out there, the arm slides back 
and forth easily.
Sometimes it won't load at all - push the load button, light goes out, disk 
spins up to what sounds like normal speed, but the heads never move and the 
Ready light doesn't come on.
There's supposed to be a Fault after 40 secs but that doesn't happen - it'll 
sit there forever spinning but not ready.
If I turn off the power and remove the pack, and pull the positioner out 
just enough to avoid opening the Heads Home microswitch (which causes a 
Fault light), then it'll spin up, load track 0, and work fine the rest of 
the day.

The manual (as usual) only recommends replacing the bad assembly for ease in 
field servicing, which is deliberate.
But I don't have a DEC repairman and a warehouse full of parts handy... Is 
there some kind of adjustment or lubrication I can do?
If I replace the positioner then I have to realign the heads (not too bad a 
job on this drive, though).
Any ideas?
thanks
Charles