It defiantly sounds like a serious issue.
I would guess it's most likely a combination of worn hammer & trigger hooks plus maybe a bent trigger pin.
A book I highly recommend for all Garand owners is Walt Kuleck's M1 Garand complete assembly guide.
He gives very detailed instructions on a complete disassembly & reassembly.
But best of all he shows how to inspect for worn out parts (with lots of pics).
https://www.amazon.com/M1-Garand-Com...assembly+guide