How to dissect a Gossen Ultra Spot (aka Spotmaster)?

My Spotmaster aka Ultra Spot meter has a somewhat sluggish function button - sometimes it works, sometimes it ain't.

While Bogen and Gossen just too happily offered to look at the meter and fixing it, they never answered on my requests on how much a repair/adjustment of the button would cost. And both carefully avoided to answer if I could perform the fix myself.
I am tempted to give it a try myself, if I could just manage to open the darn housing of the meter. It got at least two hidden screws (or something similar to that avail) hidden underneath a small round patch (no clue how to get it off) in the middle section of the housing.
Anyone here having some good hints/advice on how to to the meter's guts without applying lethal force?

Thanks,
Chris

If it is just the button that is sluggish, you might pick up some contact cleaner and light spray, you want to make sure and get the kind that evaporates and lightly spray around the perimiter of the button and work it a few times, often times this is enough to dislodge and clean any gunk up.

Dave

I have the feel, that the button is actually worn out, rather than just dirty. If I push it in really hard and wiggle it a bit, it does react (not always, but often). But I'll give your advice a try; can't make it any worse than it is.

Cheers,
Chris

I had mine serviced at Bogen in the US. There prices are all posted clearly here: http://www.bogenimaging.us/service/repair_gossen.html
If you are dealing with someone in Canada who won't giv e you a straight answer, just send it to the US. The service was superb: they replaced a scratched front element, buttons, and upgraded the display. Other than the exterior, I basically received a brand new meter back from them, and couldn't be happier.

I emailed Bogen, and I might end up using them; but their standard 122USD repair price is a tad steep, since it's just that one single button to be fixed - it better be a golden button and diamond studded for that price LOL. Too bad that I can't access the panel myself.

Cheers,
Chris