Not sdure I understand what plastic parts you're talking about. I've got a couple oif Martins; a FireCat and a Moab and the only plastic parts on mine are the shims between the cam and the limb forks. Well, maybe the shims under the bezels under the limb bolts.
As for the string fraying above and below or around the peep? Quite obvious that there must be something going on with the peep. Strings just don't fray on their own in cases like this. They get help.
What kind of peep are you using?
If You're Not Living on the Edge You're Taking Up Too Much Space
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