Unfortunately even the factory parts quality is not that good all the time now. OEM parts only for me when I can get them.

True but still usually better than aftermarket. Also you have to watch where you buy them. You can get AC Delco at WalMart but is it real ?? Same with stuff online. Dealer or AC Delco distributor only for me.

I agree with you 100%. Factory parts only when possible.

I wouldn't buy parts off ebay and especially Amazon. There are so many fake/counterfeit parts out there, it's crazy. Some look identical. Very hard to tell the difference till you find out the part doesn't fit or work. It's not worth trying to save a few bucks on.

i have had a few of these flat caps break the tang off the center of the rotor it can be hard to find as you have spark but it will not fire

I agree with SB , knock the plug gap to .035 , way less stress on the ignition.
Assuming your plug wires are good.
You will also notice that the build up on the inside of the terminals in the cap is alot less.
Marine engines run rich enough , they dont need a huge spark gap to light a emissions lean cylinder.

Any chance it's a ground issue,