Did you replace the bushing that goes through the playfield? If not could be worn weird. If you did it could be installed improperly.
Did you gap the flipper from the pf properly?
Look to see if the flipper rubber is binding on the inlane guide.
Did you change the coil sleeves?
Check voltage at the coil not the button.
Check the wiring on the coil to make sure it is correct. Previous owner could have the lugs wrong.
That’s all I got.