Challenger SB36 or MF 1840 stripper arm wear

How much wear is acceptable on the stripper arm?  I had a horrible first cutting with knotter issues.  Ended up using my old Hesston 4600 as the sb36 was leaving the knot on the billhook... see image here

 

I replaced the twine knives and baled 5 baled without issue.

 

I plan to disassemble the entire knotter and thru everything but don't want to do that until I have a good window.

 

The stripper arm has pretty good groves.. see image here  Assuming those are from twine and not built that way ...

 

I have a friend with a older side pull new holland and it makes beautiful, firm bales.  Need to work on bale quality also ...

 

Thanks

 

Challenger SB36 or MF 1840 stripper arm wear