Have to take it apart and add new silicone fluid most likely, 500K.
John, there was a thread around here once about the gummed up cam under the tonearm on the 1900/1950 and I believe it was you that had some pretty good pics of the problem area. Did you delete those pics?

Picture of stuck cam..the white one, some WD-40 took care of it if I remember right.
... But I was curious and kept going in while drinking a few more cold ones.
Barney
Btw, I just picked up an SL-1900, and the tonearm lifter is stuck in the up position too. I can depress it with my finger, but it springs back up. I suppose I may have to get curious enough to try and fix it--sans the Schaeffers, of course!
Then you can spray some WD-40 under the white plastic piece after loosing it up of course.
But you will need to re apply 300K fluid to the lift because the WD-40 will change the properties of associated components.
Barney
I'm not sure if I have any WD40 in the house right now. Which one of these from Tower would I use if I were to go with the silicone? Thanks.
... on the white plastic piece and work it back and forth to free it up and see if that helps.
I have bin using 300K lube on the tube and it seems to work out OK.
Barney