Problem with Variac/isolationtransformer

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As part of collecting the tools i need for repairing things i had bought this thing from my local marketplace; [You must be registered and logged in to see this link.]
The variac is working well but the current draw meter is not working. Can this be a problem for the working of the machine? I can live without it for now because i want to make a lightbulb tester for that application. Is it possible to break the whole machine if i keep go using it like this? I also have a very old tube tester ( 1940 ) and i want to run it at low voltage for a week for the first stage of a restauration. That means i can't be arround always to keep an eye on it. Because it is so big i'm a bit affraid to open it up and mess with it. But if you advice is to solve the problem first i will give it a try. Thanks