Recently replaced timing chain. Now leaking oil from the plugs on timing cover that allow access to timing guides. Replaced plugs twice and they still do not seal off properly. Is there a specific tool or process that I am missing?

Rubber coating on plug smashes out.

This is port where plug goes.

 

Although not what I wanted to do- I was able to fill the port with cloth then use a file to smooth the front edge to a slight bevel. Cleaned port. Used light oil and slowly tap it in. Probably not the recommended way, but it worked well and no leaks now. I guess the factory edges were sharp and cutting the rubber away. Hope this saves someone 3 hours of scratching their head like I did.