seized rear shock

[droptop]

Has anyone come across a shock absorber seizing? My spider has been making a harsh metallic groaning sound under certain braking/cornering/road surface configurations since I bought the car and despite numerous attempts to locate the problem, I have been unsuccessful up to now.
I had the car at a show on Sunday and was again tormented by what sounded like something striking the underside of the car to the rear on the drivers' side.
Yesterday, I had another look with visions of some trailing arm or mounting point broken or rusted off, but everything was solid. Too solid, in fact. When I tried bouncing the car at each corner to replicate the sound, the right rear corner wouldn't move.
Is this something common and can it be repaired without going down the replacement route as I need the car next Sunday for another show and am concerned about driving it with one unyielding corner like a go-kart. That said, the roads I will be travelling have to be driven slowly anyway so it won't be working very hard.
Any ideas?

[Charley]

I had this happen once with a shock insert. The thing stiffened up at the top of it's throw and busted out the upper strut mount. Better get it fixed or you will end up like me, with a broken mount !

[Neil-yaj396]

Same here on my old ie. Mine didn't break the mount but punched up into the boot as described above.