working magnetic drum stores?

Just out of curiousity, does anyone still have a working drum storage device? wondering if any working examples have survived... I have a half-assed plan to try and find one from somewhere at some point. We have a Sperry unit that's way beyond repair, and don't have anything other than the drum assembly itself anyway (the bearings still seem good though so I might see if it can be coaxed into spinning) - but a working demonstration would be great hooked up to one of the 1960's machines. I gather that telphone exchanges used to use them here in the UK so maybe there are still a few lurking in private hands as they must have been reasonably common at one point. The flipside of course being that they're pretty bulky devices in themselves, and with the low reliability they've maybe all gone to scrap years ago (unlike other peripherals of the area which survived). cheers Jules