I have a 1985 380SE (722.310 tranny) which won't go into fourth gear. The auto has been OK except now it looks like a new B2 piston is due (220000 kms and slipping in forward only). The fourth gear has never engaged and I am wondering if this might change when I install the new B2 piston and accompanying bush?? While doing this work I would like to try to do what I can do fix the fourth gear. Also I will check the modulator which so far holds vacuum. Any input on these subjects would be appreciated. Thanks. Ed