Play between the con rod and crank shaft definately isn't a good thing, but I wouldn't think it would prevent the engine from starting. If you can feel the compression of the engine, then obvisously the con rod and crank are staying togerther in the engine, and if you feel the compression then the head must be sealing to the motor.

What kind of electric starter are you using?

I would say 80% of starting issues are glow plug/glow ignitor related. That glow plug should glow whitish orange.

Have you tried resetting the HSN and LSN to factory settings?

Have you tried holding the throttle open while trying to start the engine?