I used MB sliding roof grease to lube my wiper mechanisn. White Lithium seems to get gummy and then dry out which results in sticking. The MB grease isn't cheap but I love that stuff.

jsbick: Take the old gear and the wiper unit to a local, old line machine shop and they will fabricate a new one for a reasonable price. Making gears is taught in basic machine shop courses so they will know what to do. I find that the older the shop, the better their prices and skills, generally.

Tim