Starter Probs

[ARTHUR, KEITH]

Hey,

The car is a 1991 Audi 90.  For a while now my starter gear has not been engaging radomly.  The starter spins but the gear dosen't pop out to spin the flywheel.  A few tries will eventually cause it to work.  I pulled the starter out and spraid silicon lube all over the gear and assembly.  Worked perfectly for about a week then returned to its old tricks.  Does anyone know of a more permanent fix?  I would hate to have to get a new or rebuilt starter to just to fix it.  
Thanks
Keith