Extractor Plunger

[tag173rd]

I have an 870 Wingmaster 12 ga. I purchased in 1965. Had a hang fire and a failed (split) hull. Lost the extractor claw and the plunger. Found the new parts I needed but found the plunger was of larger diameter than could be fitted in the spring hole? Did the earlier 870's have smaller diameter of the plunger I checked schematics for the 870 could find any difference? Thanks Turk