>>1798680Sometimes stiff links can be fixed by flexing the chain back and forth (not in the direction that the links rotate, but rather perpendicular to that, side to side)
Also while the masterlink looks fully seated in place, it would be worth a try to also try pulling the chain away from the masterlink (in both directions at the same time) with a lot of force
Besides that, lube your chain (which will also serve to clean it), read
topnigger.ueuo.com for detailed lubing instructions
Also look closely at the masterlink and see if it says what speed it is for (i.e. "8sp") and if that matches the number of sprockets on your cassette. While 5-6-7-8 speed are generally all cross-compatible, anything above that needs its own speed, i.e. you need a 10sp masterlink if you have a 10sp cassette, etc. If the masterlink is the wrong speed then the shop fucked up.
Also, since your chain broke, chances are it is stretched and in need of replacement, and if you keep riding a stretched chain you will fuck up your cassette sprockets, so you should likely get a whole new chain. Measure it for stretch if you have a chain checker, otherwise ask a shop to measure it for stretch. If it is beyond 0.75%, replace it.
