Burroughs BU4400 tape drive. What is it?

Quoting Chuck Guzis via cctalk <cctalk at classiccmp.org>: Looks like you're right! I'm pretty sure it's a cleaner. Everything on it seems to work well, once I figured out how it was intended to work. Just had fool the tape optical sensor (BOT/EOT?) with a piece of paper and it started up fine. It only seems to want to go 'slow' in reverse, but that may be something to do with the lack of tape. I like the tape counter a lot. It shows error codes when they occur, and is a dot matrix style LED display (perhaps not true dot matrix, just something nicer looking than a 7-segment display). So, that's good news - to demo it fully all I need is a reel of tape, rather than needing to find or implement a controller as well. I'm in New Zealand, but I think I'd be lucky to find anything here. As a fallback, there is plenty on eBay, at least. If anyone has some damaged or otherwise unusable tape that's only suitable for demonstrating a cleaner, please drop me a note. Cheers, Mike