Nice collection you have there. Yes, this can be addicting so be careful and do everything to avoid an "intervention" from the other half. I have found that if you can fix some of them and sell them you will stand a much better chance than if you just collect them and let them clutter up the place.

The first one, the Craftsman, appears to be missing a plastic cover that goes over the recoil. Some of the plastic covers are screwed down and some just snap in place with retaining fingers. Get the model number from the deck and go to Sears website where you will be able to enter the model number and pull up an illustrated parts list to find the missing piece.

Good luck and have fun.