1986 300sdl fuel injector and compression testing question

First, I was removing my fuel injectors to do a compression test, I looked in each of the pre-chambers for oil and carbon (as instructed). I found what appears to be in inconsistency. when looking into my number 3 pre-chamber I see a normal appearing tip of the glow plug and another "thing"--it is bulbous in the middle and then thins out as it goes toward the ends of the chamber (on the "normal" five chambers. But in number 3, it appears that in just this chamber the part does NOT to extend all of the way through the chamber on both sides (only one side). Is this normal? what is this part? Should I be concerned? (i have a picture but i can't figure out how to load it into this text box)
Second, the number 3 cylinder tested 320 psi (which was on par with my other cylinders) but number 5 was slightly lower at 295, so I added oil and blew it out. Then I re-tested it, my meter read 490 PSI--is that possible? I suppose this result reflects that my piston seal is not in great shape, correct?

Thanks and Happy New Year.

Scott

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