1988 245 w/ AW70, approx 250K.

Car is very reluctant to make the 1-2 upshift when in D. Will shift if you let up on the pedal, otherwise will stay in 1st gear up to 4K rpm. Otherwise shifts fine both up and down. With gear selector in position 2, it makes the 1-2 shift perfectly. (Discovered that by accident, after having done the flush etc. below)

Have already flushed with synthetic ATF, draining the pan first, and shifting into D and R for several seconds each during flush phase. No improvement.

Kickdown cable is adjusted so it is quite loose, hoping to encourage early upshifts. Shifts are smooth and early and right where we want them, except for the 1-2 when in Drive.

Replaced the tranny mount today, as old one was squashed and had slid so the two studs were offset by about 1/2 inch. No improvement.

There is a bit (2-3mm, probably) of play in the shift linkage, and I am wondering if a bit of slop plus some mild mis-adjustment might be to blame for the problems in drive. Should my next step be new bushings for the linkage?

Am I correct in thinking that because the 1-2 shift works correctly in position 2, I do not need to be worried about worn check balls in the valve body or other internal mechanical faults with the transmission?

This is a friend's car, and his primary means of transportation, so I would like to get this sorted out as soon as possible, and any thoughts on how to proceed would be appreciated.

John