A 2-3 shift flare before or after overhaul is a common complaint with the FNR5/4F27E transmission. Even a slight flare can be accompanied by codes for gear-ratio error and solenoid function. The cause for all of this is usually a worn servo-pin bore where it goes through the case.
A 2002 Ford Explorer with a 5R55W transmission came into a shop with a complaint of no 2nd or 5th gear. Gear-ratio-error codes P0732 and P0735 were stored, but so was code P0775, indicating a problem with pressure-control solenoid B.
We all know what gear-ratio-error codes are all about by now, but that P0775 code – that’s a humdinger.