I purchased a set of new glow plugs and began changing them out Sunday afternoon. Did the passenger side firsts, took all of 25 minutes. Went to the other side and ran into some problems with # 6 & # 8 on my engine. All of the old glow plugs(Short) came right out but I could not get the new glow plugs(Long) to seat in # 6 # and #8. It seemed as if the tip of the glow plug was being obstructed inside and it wouldn't quite reach to the threads I cleaned two of the old glow plugs and they went right back in no problem. So, now I have 6 or the 8 new glow plugs in and my truck starts in a 1/3 time as before. I'll go back and try again but thought I'd check and see if anyone else has run into this problem???
86 suburban, 6.2

Thanks
Brian