What size wrench are you using on the drawbar ? As in, length of handle ? If you are using the little 6" long wrench that came with the machine then I agree that the drawbar is not tight enough. If you have a torque wrench it would be interesting to find out how much torque you are getting with a firm crank. Tighten as usual then loosen with the torque wrench to find out what you have been using.
I also have never had a TTS pull out and I have done some pretty serious cuts.
I also think you may have misread the use of the lapping compound. You would put it on the shank of the TTS not the endmill and only if all other reasonable means failed.