The window regulators on the older (89 -94?) Geo Metros wear with time – this is two lubricated tracks that guide the parallelogram that keeps the window level as it rolls up. On the front door, the glass is to be firmly seated in the track at the rear of the window as it rolls up, and to do this the parallelogram must be canted backward. This eventually gets sloppy, and the two mounting screws are fixed into vertical slots in the inner door sheet metal to adjust for this wear. Lower the rear screw and raise the front one.
I ran out of adjustment on my car (93 Metro), so I drilled a new hole just below the rear slot to put the screw through, and now the glass rides up without jumping the track. While you have the interior door panel off, lube the parallelogram tracks and spray the glass tracks with silicone lubricant (NOT regular grease, which on the rubber turns into a glue) to make rolling the window up easier.
I did not find any wear or disintegration of any of the window track channel rubber; of course your situation may be different.