Well, mine too came with a lot of compound in the joint. So much so that it had to be pushed from half stop all the way to open. Flushed it a few times and it improved. Carried it for the last 5 days, cut everything from cucumbers, apples, and tomatoes to shrink wrap, banding, and boxes. It preformed flawlessly. Over that time the action continued to improve, so much so that it's almost spot on at this point. Smooth and snappy.
Interestingly enough I've had similar experiences with every 77 that I have owned (1st in 2019). Fairly unremarkable action out of the tube, then with flushing and use they become smooth as silk with some of the best action. It makes me wonder if the 77 pattern is prone to catching more compound than others or if I just randomly caught 4 outliers? Anyway, don't give up on the run they may need just a bit more love.