Pentax F 70-210 with a screw loose

Hi,
I've got an F 70-210, a screw has come loose and is now rolling around just inside the mount. The lens seems to work fine, apart from occasional jamming of the aperture ring, presumably as the screw gets jammed inside. I've put a couple of pics here showing the screw, I think it has come out from pretty much directly beneath the position where it is shown in the photos.

https://picasaweb.google.com/112721048137835603524/15August2011?authuser=0&authk...

I figure I have 2 options
1) Keep using the lens with the loose screw, aperture ring will nearly always be set to A, so hopefully wouldn't be a big problem

2) Attempt a repair. I've found some pictures of a disassembled 70-210, it sounds like the mount comes off fairly easily, but has anybody got any practical experience of doing this? Are bits going to fly everywhere and leave me with a useless lens? I'm reasonably practical and pretty confident I can make the repair, but would really appreciate any hints and tips people have

The big question could be where has the screw come from?
A lot of mounts come off quite easily - provided you don't pull the aperture ring off as well (tiny springs, tiny balls ... oh "bother" :blush but to find where the screw has come from you may have to go deeper, and that coud be a tricky job - and one for an expert.

If you can see the screw, a tiny bit of "BluTack" on the end of a bit of stiff copper wire can maybe fish it out, or maybe a magnetised screwdriver will get it. Then put the screw somewhere safe against the day when more drastic treatment is needed.

Figure: if the value of the lens is more than the cost of repair - leave it to a professional. If the valueof the lens is less than the cost of repair, AND you are prepared to scrap it if things go wrong, then have a go yourself. But if you can get the screw out without screwing something else up, then just carry on using it.
Geoff

Thanks for the advice. Invested in a couple of tiny screwdrivers and have managed to get the screw back in its proper place, no flying springs or loss of mini ball bearings.