Plastic ring around drum is all chewed up and flaking off

It sounds like the drum has broken from the rear mount. This will chew up the outer shell. This is a very labor extensive job. The parts are expensive also. You will probably need a new outer shell and inner drum.

The should be a plastic or steel ring around the drum and the seal take that off and the seal should come off.

then just put the new one on and put the ring back on

It can be replaced. Here's a link to your manual for the dryer, which on the 2nd and 3rd pages has a diagram of it and a part number for you...when you have your part number you can order it either directly from Electrolux or find one on Ebay or another online source....if you have a local appliance shop you may be able to get one there as well....here's the link:
http://manuals.frigidaire.com/prodinfo_pdf/Webster/5995396412.pdf

The small blue wheel, just next to the Motor, is the tension pulley, your belt should go around it, before going around Drum

did you ever get a solution for your problem with your dryer? i have same frigidaire dryer model number and the plastic ring on the front inside just broke off in mine last week and im not sure what to do to fix it.

will the plastic ring in the second ring move to the other ring . the danger is if you put the spring in the second ring the drum may not be line up straight when you look from the top (the motor may be further back) causing the motor and back to rub on the back plate when loaded might be better to drill new hole ?

>>A repair man replaced the plastic ring but the gap is still there, ruining several items per load. Is it repairable or a fatal defect?<<

The repairman should check the drum rollers, the guides, and the baffles to be sure the dryer drum is rolling true (round). Also, the replaced ring should be re-checked to be sure it's installed correctly.

theres arubber "boot" connecting the tub to the outer wall of the unit. if your seeing "bone colored" plastic rubbing off and onto the soft rubber boot assy, that sounds like the outer tub itself somehow wearing down, , that snot an easy repace ment at all, you would need to replace the entire outer fornt tub.