I have this exact same camera and yeah, I think a CLA is in order.

When I bought mine the first thing I did was send it to a camera repair expert and had it fixed up. It has been trouble free since that day (about five years ago) and gets regular use.

The lens is pretty damn sharp so I'm suspecting an alignment issue. Wide open it might be a tad bit soft at the edges, but it should still be nice and sharp in the center. The Tessar lenses are quite nice and I would put them up against just about any other lens I own.