I cant help with the seal numbers, but a suggestion… I would check the valves on the intake of the motor. My Martin 45 has O-rings, one on each valve, that were hardened and cracked from age. I ordered new ones from Russ Larson (Martin guy) and replaced them. My old, original O-rings leaked crank case pressure terribly when the motor was pulled over. This would be the same scenerio as leaky crankshaft seals, only worse. I believe some early Martin’s had regular valves without O-rings, and some had O-rings… I’m not sure on your 100? Might be worth checking into. The other thing I found on my 45 was stuck rings. I had to remove the exaust cover,
and sprayed it liberally with Mercury Powertune. After soaking a few days, and with a little help working them with a small screwdriver, they finally freed up. That motor will idle down now, like a modern 4 stroke. BTW, be sure to reinstall the valves in the original holes that they were removed from. In other words, don’t mix them up. Hope this may help!
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