Based on some Internet research, I used vinegar to clean the corrosion and it worked very well. I was also able to take off the base plate which made cleaning out the battery compartment easier. I ran a roll of very expired Agfa APX 400 through it (I found this film in a desk drawer in school about six years ago; I think it had been sitting in the drawer for some time). The negatives scanned somewhat light, but I was able to fix that. It is possible that the meter in the Hi-Matic is less than accurate particularly since the battery that it is designed to work with is no longer legal.
Here are some pictures from a visit to my grandparents' house. For an old beat up camera and expired film, I was happy with the results.
Outside in the backyard:
One from the kitchen:



