Grabbing spares from the yard is a good strategy. Most aren't bent and any regulator from the correct model (126 into 126, 123 into 123 etc) will interchange. Regulators are door specific and the number of teeth on the motor changed over the years. Get the motor with the regulator, clean and lube the tracks and the window should work well with no slow spots.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Ive located a set of 300cd WRs on amazon new,just google it ,theyre not too expensive,for quality ,I cant speak of but Im sure about a willing participant to try something at this point ,very old car and windows Rs are important .For the 300d their much more reliable due to the lighter glass being pushed ,the motors arent usually the failing factor ,the wear is the torqueing and like you say not enough grease will start to bend and weaken the rugulators ,really good window motors in these cars!
Edit ,thats gone ,nooooo! cant find them on the site anymore ,should have bought the set.