Mercury Outboard 140 spark issues

Hello everyone i am new to this forum and new to boating. I tried looking through this forum and others to resolve my issue on my outboard. I believe i have a 77 merc 140 tower of power i cannot locate a nameplate anywhere on this motor. I was only able to find a few numbers on the block which are 8527738 and 62301. I suppose one of these is a serial numbe.
Anyway to get back to the problem i am having: with everything hooked up my motor is turning however i have a spark issue. When i do a spark test with a plug unscrewed connected to wire and held against ahe frame i only get one spark. Sometimes i get it when i am switching my ignition from on-off and off-on but no continuous sparking when motor is cranking. I already know my coil and control box are good as i conducted some tests that i found on youtube so i have continous spark when doing those tests. I also conducted a trigger test and i assume i did all those tests right and still the same problem when everything is hooked back up. Im willing to take any advice. Here are some pictures of what the motor looks like

Look inside the distributor cap and make sure that carbon plunger is in place.

Jeff

Already cleaned that and the little spring as well as the bottom of the rotor contact and all the contact points on the cap and no luck. The spark comes at odd times when first turning the key to the on position then cranking gives me no spark and then i get a spark when turning the key to the off position. I am lost at this point. Also tried to post some pics from my phone but they are not uploading idk why