grizzly 660 counter ballance chain

Hello, I’m new to this site and also just picked up a 05 grizzly 660. I took the engine apart (the owner ran it out of oil). I found the rod seized to crank, piston broke and cylinder scored. But I also noticed that the chain that goes from the counter balance gear to the oil pump gear is real loose. I couldn’t find much in the manual about this. so I am wondering if this is normal? Thanks for any help!