Was the bolt closed (ie forward into battery and down) when he bought the gun? Does he remember that lifting the bolt one time (the time before the problem occurred) was different than previous times. I'm betting on rust or a broken firing pin spring.
Even if the solvent soaking frees up the bolt, if it was my rifle I would want to see what had caused it to jam up before I fired it again. Take it to a gunsmith and see what he says.
JohnDog (I get coffee in bags )
