Found a Micronta VTVM

[Eric H]

Picked this little gem up for $5.00 at a Thrift Store.
It had something banging around inside that I thought might be a battery and it was, a "C" Cell Duracell that expired in 2000, it's not leaking though, not even dead for that matter, my meter shows 1.8 volts coming out of it!
That doesn't sound quite right but it makes a speaker pop so it has something in it.

The VTVM doesn't seem to work, unless the battery needs to be in place to do so? It'll Zero but I get nothing measuring DC volts.
Maybe it needs recapped.

It uses Telefunken tubes, one of which is a 12AU7, have you priced Telefunken 12AU7's on eBay lately?