trouble letting windows down

[jhrusk]

working on a 72 chevy pickup,windows are extremely hard to roll down,seems like the window is tilting as it goes down causing the rear edge to grab into the rear channel liner.regulators have been replaced with aftermarket .I was wondering if someone had any original regulators they could measure the size of the rollers.I am curious if they are close in size.seems like there might be excessive play in the tracks. thanks.