my 67 had to old quarter window takes two hands to get up problem, er i should say to hands to roll up problem

so i just replaced the lower rollers as that seems to fix the problem for most people,
well i am not so lucky, my quarter windows still need some help to get up
i believe the problem is that the upper 2 rollers are also worn but i cant seem to find anyone who sells them, or am i not looking in the right places

does any one know who sells the upper rollers for rear quarter windows?

or does anyone have any other suggestions as to what else should try to fix the window problem?

thanks everyone
Jon