A handy person from Victoria Point Queensland says:
March 31, 2018
I have 3 sets of 1/4 round showers. Some of the nylon wheels/tyres have cracked and need replacement. I want 6 units. ...................................................... Left to right.. Nylon wheel.. spacer..off set cam (raises and lowers glass when adjusting screw on right is turned)..locking nut..adjusting screw cover. I believe that these units we made in China. Can you help?
Tom from SWISCO responded:
April 3, 2018
I'm not sure if we have an exact match for this roller, but I've made a list of possible replacement parts on this page. Look over the hardware I listed and let me know if you could use anything here.