1) magnetos attract all the grease, dirt and crud available so my first suggestion would be to spray magneto assembly with a nonresidue elecrical
contact or electric motor cleaner...strong stuff that probably is not
good for your health so be careful. This may or may not cure the problem
but it will remove the gunk that can hide problems.
2) a small engine repair shop can probably test your coil for a small fee
and if bad perhaps supply a replacement as it is likely Tecumseh used
same parts on a lot of small engines other than outboards. If not Eska
made a lot of outboards so a parts motor should not be too hard to find.
Cleaning and checking coil out should help narrow down possible problems
so what is left is polishing & setting points and checking wiring to
rule out bad insulation. Try a new condensor or having old one checked.
I am surprised that no one else responded. Magneto is not my strong suit
but I have done lawnmower and snow blower engines with good results.
Once you have attempted something outside your comforts zone and it
turns out well your comfort zone expands. Sometimes things do not work
out as planned. Do not let that stop you. Learn from your mistakes,
experience enables you to succeed at what others will not attempt.