Chain Question

Is it that the stars are worn out of the screws, if so a little trick I learned a while ago was to drill a small hole in the head with a 1/16 drill, and with a good screwdriver belt it in a few times without trying to turn it.

This puts some fresh indentations in the head and may allow you to remove them with an impact scredriver.

Warning dont drill too deep as the head may shear off.

Failing that drill the heads of the screw off and then remove after you get the cover off with pipe grips (multigrips).

Again... dont mix new sprockets with old chains, all should be new to save $$$$ down the road.