I just now need to replace the original bronze zinc holder in my tube stack. Everyone sells a NPT 1/4" zinc holder but the original is much smaller. the 1/4" only goes in one thread by hand and has 7-1/2 threads in the length the original has 8. Small end dia. .523" - orig. .505". Does everyone re-tap the hole to 1/4"" N.P.T. ?