O rings can be easy to replace but getting the size right can be a frustrating initial cost. For standard TM MWS mags, I use m4 x 1 and M12 x 1.5.
For the nozzle, which brand of nozzle did you replace it with? Some brands like angry gun have a higher failure rate than average, but it can also be caused by loading the magazines to max capacity which then puts upward pressure on the nozzle, leading it to come into battery at an incorrect angle and break