High beam flasher control works only part time. What to look for and how to fix. Am pulling spring loaded turn signal stalk all the way back (toward driver). Wiggling while in back position doesn't seem to matter (i.e. loose contact, etc.). No difference if headlights on or off. All other functions on stalk work properly. Car is 1993.

Since you state that all other combination(turn sig) switch operations, then it has to be the problem. Somewhat common failure, had to replace one on my sons 190E due to no hi-beams at all.

Had to replace my turn signal switch too. Identical symtoms, interm. high beam, part was $149.00