Another Rescue Mission

This beauty from the GDR was headed for the knackers yard. Jena aperture blades seized,film advance leaver wouldn,t return,the meter was dead and the body had suffered years of neglect.
I fixed the lens and return leaver.All the body needed was a good cleaning (windex & Q-Tips). Got the meter fired up but,man,its way outta wack. My question is this: I have heard of "stoped down metering".Can I use the depth of field button to establish the proper exposure? If not can anyone suggest how to fool the meter? (it seems to be off by about 3-4 stops).