Timing Chain Problem

[NikNacs67]

My brother just bought a '93 300ex today but the past few days we've had the motor apart to figure this problem out. When the kid my brother bought it from bought it a couple weeks ago, it was ticking really bad so when he went to park it, it just died. So he took the top end off, saw that the chain had slipped off the cam gear so he put it back on, tightened it up with the tensioner, ran it for 5 minutes and it did it again. So I bought a new chain, took the clutch cover off and here's where im stumped. There's a gear underneath the bottom gear for the timing chain that I can't figure out how to get off so if anyone knows, lemme know asap.

[Silverfox@C&DRacing]

not sure if this is what you are asking, but you have to take the clutch basket out, then you have to remove the oil pump assembly and then the gear comes off and the chain will go behind that. Another thing you want to check is your tensioner (the one that goes in the back of the motor that keeps the chain tight) make sure it is working properly because they do go bad.