Had the very same problem this past week - brand new out of box Earthquake - tight to pull, refused to even come close to firing up. Redcat James - must have been you I exchanged emails with.... (thank you!)
Anyway, actually tried afterrun to loosen things up, and leaned the engine, a bit, etc,etc. and eventually gave up and shipped it back and got an electric model ordered..
I still am on the prowl for a nitro. But this one wasn't it! Never had that kind of trouble with a Nitro before and I've had many in the past 10-15 years. Spent 3 days until my hands literally bled.