Burroughs BU4400 tape drive. What is it?

[mike at fenz.net]

Quoting Chuck Guzis via cctalk <cctalk at classiccmp.org>:
> Judging from the controls and lack of mechanical buffering, I'd
> pronounce this to be a tape verifier, or possibly a cleaner.  The "half
> cycle" and "slow" are clues.
>> I just bought this Burroughs BU4400 tape drive:
>> https://www.trademe.co.nz/Browse/Listing.aspx?id=1999913439

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