also - whilst you are trying to fix this, could you attach some cardboard (with jute or sisal etc) along the barred part of the cage and your hammy can chew that instead of the bars - obviously they will get thru the cardboard at some point - but you could also try something like this and attach it to the bars
https://smile.amazon.co.uk/gp/produc...?ie=UTF8&psc=1
these may help long term or at least short term till you can figure something out