Thanks to all the posters for the great information here - really helped me a lot getting my Tobeco going.
Question: Is your #4 slip ring thick enough so it comes up above the top rim of #3 and #5 sits on it?
I think this is how it should be, otherwise #3 and #5 are metal-to-metal which doesn't seem right since they have to turn against each other as JC opens and closes. The #4 that came with my Tobeco sits below the rim of #3. (All things happen for a reason I guess)... The first thing I did when I got mine was lose #2 down the drain cleaning it (stupid me). I wasn't finding a complete spares kit in stock anywhere, but I did find in this thread that EVcigarettes.com had individual EHPro replacement parts. So I ordered a #2 and also a #4. Ah! The EHPro #4 ring is thicker than the Tobeco and the top of it is just above the top rim of #3 so that #5 sits on it. The EHPro #4 is also a whiter material, it looks more like the picture of the spare on the original's site. I did find and order a complete Tobeco spare kit in the mean time, so I have another Tobeco #4. Here's what I measured:
#4 that came with the Tobeco: 1.35mm / 53mil thick
#4 from Tobeco spare kit: 1.35mm / 53mil thick
#4 EHPro: 1.56mm / 62mil thick
Measuring the height of #3 without #4 in (not including the 510 thread part): 6.25mm. Same, with the EHPro #4 in: 6.31mm. So the EHPro #4 is .06mm / 2mil above the top of #3 and #5 slides nicely on it. Seems like that's how it should be. From those, the "ledge" that #4 sits on in #3 is 1.5mm below the top and the Tobeco #4 is .15mm below the top of #3.
I did have to thin #7 to allow JC to turn freely with #9 tight. Both the #7 that came with it and from the spare kit were .94mm / 37mil. I thinned to .79mm / 31mil, so down 6mil. Would have only needed to be down 4mil without the extra 2mil that the thicker EHPro #4 added I guess, but it still would have needed to be thinned.
I want to get another V4, I really like it. But if I get another Tobeco, which is fine otherwise, I need to get an EHPro #4 to make it right? Maybe it doesn't matter if #5 sits on #3. I haven't seen anyone else mention this as a problem. Comments? Do your #3 and #5 contact? Maybe I'm just too picky...