I recently serviced the NRV on my Primus No. 2 and decided to reuse the pip because there was no pip holder, as it had one-piece moulded pip that fitted straight into the spring. The pip seems OK and I reassembled it and fired up the stove, which seemed to be OK and there were no leaks in the pump tube. However a few posts on this forum have made me wonder if I put the pip back the wrong way round! I inserted it into the spring correctly, so it sat against the spring, but does it matter which end of the NRV tube it sits against? (i.e. the slotted end or the raised end that you fit the removal key over) In other words, is there a wrong way round?