I recently aquired a 1973 Eldorado convertible that is not running, previous owner's mechanic said the timing chain is bad. I pulled the balancer, hub, timing cover etc. I'm trying to check the timing marks before I remove the old timing set but I can't find any marks on either gear. The cam gear is missing a little of the plastic or nylon. I did order the roller set with 3 keyways. Any help with diagnosis would be greatly appreciated!