My guess is that the meter quit working for some reason?
Did the meter work in any of it's functions?
Near the bottom of this page is a list of repair sources for the Drake meters;http://www.wb4hfn.com/DRAKE/DrakeArticles/TechTips/DrakeTechExchange.pdf
Other than that, I'd look for a parts rig on eBay.
I would also check with any Drake Yahoo user groups. There are probably more than a few.
The ones most closely relating to your Drake and/or having the most members are the best bet.