I think the season 7 "SKI SHOW" Feb/82 with L&S trapped on chairlife and later flighting in snow was the last really great physical comedy show they did.

the next time they did anything physical together
was the season 8 "Window on Mainstreet" episode Oct/82
when they are on display to public in window and act like chickens under hypnosis -- (okay but not that funny)

Shirley is visibly pregnant (though they do not discover this news until end of episode--it is also Shirley's last appearance)

The think the SKI SHOW was the last hoorah of the dynamite duo of slapstick. Laverne pushed Shirley into snowbank-and it's funny.