They are easy to do. Pull te flywheel, drive belt & the four screws holding the distriburer to the drive unti. Pull the distributer from the engine & now you can check everything with a meter. I’ll bet you need to remove the drive unit & soak in solvent for a few days to clean the bearings & regrease. What color is your distributer cap? some had problems. Next replace the capacitor (condenser). & check the coil with your meter. If tun not connected to the spark plugs, all of them running the coil may be bad. Cleaan everything up, check the   cap for arcing & you need a rotor puller to remove from the shaft. Once the distribeter drive spins freely regrease as it’d always forgotten in maintance. I’m suprised you read about the points tension, very few read that. All the tool is spring tension gauge. If not set correctly it will wear out the rubbing block on the points changing thec dwell & destoying the pointd or if too weak the poits will float. There are sourses to fix the mag out there & I found a point tention tool easily on line. Any questions ask here. It’d not as bad as it loks to do oce you have done one.P.S. replace the distributer drive belt too! Do not try replacing the bearings in the distributer drive unit, they are a night mare to replace. Mercury sold a new drive unit if the bearings went  bad. Been there done that!!

Jeff