Hello I've removed my drivers side valve cover due to rattling noise and found the chain cassette exploded so I proceeded to remove the front of the engine down to the balancer pulley, which I think I need a special puller, [2006 Ranger 4.0 SOHC], am I going to be able to slide in a new cassette with the head in place, do I need to replace the chain also, whats this job like, could the motor be pooched[bent valves] although still ran fine. Any direction would help me here, thank you.