Off my chart, but the ATSG book suggests for "no upshifts":

- Check regulatiing pressure, if none, check operation of centrifugal governor and make operable

- If regulating pressure OK, disassemble/clean or renew shift valve housing

Sounds like you need a competent trans shop. Good luck.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe