One thing you will find as I suspect these older primaries with the set screws for the rollers AND the clutch weight will be hard to come by, is that the primary may not have the roller set screws but will have them for the clutch weights. This is the original primary I am replacing where the moveable sheeve cracked; will keep since the spider is good:
View attachment 179864
If the primary you are looking at is still loaded (ie. weights, springs, etc), the roller set screws may be hard to see but should be visible; or lack thereof:
View attachment 179865
