Whining from the blades/belt
A loud whining noise has developed on my 52 inch Hustler Fastrak. It stops when I disengage the blades, and is not constant - it sometimes occurs more on cornering, but can be pretty loud when mowing straight. I have just removed the belt thinking that I needed to replace that, and I found that the two outer blades spin freely, but the center blade is somewhat stiff. I can turn it by twisting the pulley, but it won't spin on its own.
Is this likely to be the cause of my whining noise, can I lubricate it, or does it need to be replaced. Is this something I can do at home, and are there any instructions on how to do it?