700r 1-2 shift. Flare? Slip?

[weq92f]

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Under light to medium acceleration, the tranny shifts good, at the proper speeds and works well. However under WOT, the 1-2 shift doesn't happen unless I lift...and I lift because it just feels wrong!

When the tranny goes to shift 1-2 at WOT, I can feel the acceleration wane then when it should shift the RPM stays where it is ( maybe rising just a bit ) and it very slowly engages 2nd. So slow that it isn't really a shift but more of a slip-into that feels to me like it's gonna break the thing unless I lift.

I took the pan off this weekend. The fluid was good, no off color or smell. The pan was clean aside from a decent amount of material on the magnet. I'd say the tranny has 8k miles since rebuild. TV has been adjusted as directed/researched/felt good to the point where 1-2 shift is pretty solid up until WOT or close to WOT. Running a BTO ratchet and cam.

Any guesses? Would a shift kit install be a waste of effort here? Should I just punt and take it to a shop?

-klb