Retarder operation with manual dash lever

[wl89spman]

My 89sp, with CAT 3208and Allison retarder, quit working a few years ago. The
way it worked was with the 3 POS sw(ON/OFF/APPLY) in the ON position, I could
move the lever from the up position to slowly down and the more I moved it down
the more braking I got, was great for trafficand stop signs. In the apply
position I got immeadiate full braking with the lever in the up position.
After it quit working it would not react to the lever, but still worked in
apply position. If I understand correctly.. the apply pos. is electric and the
lever operarion would be air...correct?

Has anybody had this problem or know what to look for? Just got it out of the
shop...and the retarder still doesnt work with the lever only. The tech didnt
know how it was supposed to work. the lever is supposed to save brake use
correct?

any help would be appreciated
Ed Gardels 89SP
oven like Arlington, Texas