HP LJ 2100 grabs multiple sheets at manual tray

On our HP LaserJet 2100 lately . . .

Multiple sheets are sometimes picked up simultaneously in the
MultiPurpose tray (the manual feed tray), wasting papers, and more
severely impacting 2nd side prints in two-sided print operations.

Are certain rollers cleanable to fix the situation? Might we spray a
polymer such as Armor-All (auto vinyl restorer) on internal rollers &
pass a few blank paper sheets to clean excess oils? Such would require
opening up the printer, but the warranty is gone anyway.

Help!

- GeneM