When you next raise the sail, done while the topping lift is either at its usual position or raised slightly and both choker and mainsheet are slack, take a look at the sail. There should be no scallops between the sail slides and the top should be near (but not at) the upper end of the sail track.
Just a cross-reference in case of interest – I mentioned a few posts earlier in this thread that I was installing a boom extension. I’ve got some questions about it, and don’t want to hijack this thread, so I started a new topic: Installing boom extensions