You said in your original post that the "wipers will be going too fast for 3 weeks or so". Are you saying that you don't have low speed as well as no intermittent wipe?

Your circuit board looks slightly different than my '76 besides having 2 relays. Don't file the contacts. You could use a narrow strip of 600 or finer sand paper doubled over to run though the contacts. Clean the contacts after by running a piece of paper through (could be soaked with alcohol). Slight looseness of the contact pivots is normal.

If doing any soldering you must add some fresh electronic grade solder. Reflowing alone is not adequate.

Your relay coil resistances look good.