Do a Google search for W123 locking eye kit. You'll find an outfit in Thailand that sells them. Their website is kind of wonky but it works and you pay using Paypal. I ordered one of their kits and it came promptly and works like a charm.

Read up on how to pull the strikers and avoid rounding out the 5mm allen head bolts - use heat or impact or both, like I did after ruining the first one. Had to drill it out. Also there will be shims to keep track of. Also draw a line around the striker plate so you can get it back on in exactly the same position it was in.

Once you get the strikers off it is easy to pull the rubber inserts out and install the plastic locking eye which will probably be totally or partially missing.

It's an easy repair and very satisfying.