here are some pictures of my old Evinrude 25hp outboard. I believe it to be from late 70s/early 80s. During my last service, the engine back-fired. We think this has been caused by some corrosion (circled in red in the first two photos - the other two photos are to illustrate which bit of the engine I'm looking at). Basically, these two bolts have nothing to screw into, which appears to be letting air into the system. I believe these bolts may be holding the reed plate in place - but I'm not sure.
The component which is corroded - is it replaceable and what is it, if I can get one?
How much work, and thus, approximately how much would I be looking at to get the job done?
Should I just cut my losses and get a new one?
All help gratefully received, as ever.