??---The 2 piece driveshaft leaks.----But the crank holds it in position and then it does not leak.-----And 25 year old motors with some hrs on them will show wear on the seals and it is best to install a kit.
Well it should fire with fuel in the bore.----Crank seals are not involved in 2 stroke compression.----I say you have weak spark.----Does spark jump a gap of 1/4" ( 6 mm ) or more ?
Stop guessing.-----Load test your battery---FREE service in most places.------Take starter apart for inspection and ohm test on armature.-----I say motor is not turning fast enough for magneto to be happy !!!
A good unit will shift to neutral after one turn of the flywheel.----But it may still turn when on a trailer with no load on the prop.---Just the nature of the gears and bearings in oil.
A 2 stroke in good condition does not load up.----But everyone has an opinion on this topic.-----I also troll ( 3000' elevation ) with a 1963 model 10 HP Johnson.----Trolls hr after hour on 24:1 ratio !!!
Work carefully.----You might want to pressure test your tank.----If there are leaks then replace the tank.----Or wear a parachute if you go boating with a leaking fuel tank.
Often times you just need to open the low speed jets 1/8th turn at a time till bogging stops.-----What are the compression numbers.----Did you install a new water pump impeller??