West Germanic infinitive suffix
!אוי וויי Do PG appendix pages exist for all those suffixes? And was the merger complete (I guess as -en) in MHG?
It was probably mostly complete. It's possible that -jan was still distinct after -r-, as it was in OHG. Look at swerien or werien. I think we do have appendix pages for them: *-anan, *-janan, *-ānan, *-nanan. The original suffix -ną wasn't productive anymore and only occurred in a few single-syllable relic verbs.