hey, I'm not saying I'm a guru in Pulsars, but I know a lot and in big part thanks to Phil himself. Phil might not be responding, not because he doesn't want to. Nobody must be online all day long... (ps. I've just found out that Ledwatch has been banned from this forum).
I'm not saying that I know the details of the P1 which Phil had sold, but I have two eyes and some knowledge. So far I had one P1 in my own hands and seen at least 5-6 others on eBay and collector websites and all had the 2800 module.
The modules have been discussed many times on the forum. The early P2 watches were fitted with the 2800 modules (with space for one reed and horizontal sensor) and they were sold after the P1 hit the market.
The 2900 module was introduced approx. in the 2nd quarter of 1973 (with vertical sensor and space for two reeds so the same platform could be used also for the P3).
I had a few P2's and one numbered approx. 28000 had a 2800 module and a later one numbered 33000 had the 2900 and the swap was made approx. mid 1973 based on the sales documentation for these two watches. Also the P3 was introduced around this time so it didn't pay to produce both the 2800 and 2900.
So this P1 was either returned for warranty service and fitted with a later module or it was repaired long after. And no, I'm not saying Phil tinkered with this piece. However a 100-300$ P2 can always be robbed to bring a 10.000$ P1 back to life.
Everything was clearly visible on the pictures so if the seller is happy with his purchase then everything is OK. I don't think a yuppie had won the watch as that kind of person wouldn't even notice the difference. A led collector should have easily noticed the vertical sensor and thus was probably aware of this.
And yes, the case can be opened. Pulsar didn't have the intention to make an "openable" watch, however it can be opened as it is soldered together.