I have been working on my 24 T off and on over the last several days trying to get it to start consistently in cool weather. Yesterday I pull started it initially then hand cranked it. It kicked back but no harm done. I have never had it do that before and was puzzled about this new development. Last night in bed it dawned on me that I should check linkage going to timer. Sure enough it was disconnected and the timing was advanced almost all the way. Ouch, that could've been nasty!! It taught me a lesson about Lizzie, she will bit you if you get careless!
Also be sure the rod doesn't contact one of the timer terminals. BTDT.