Well.... I finally got the stuck bolts to move and remove the chain cover over the weekend. I did take some photos of the chains and sprokets on the phone, but it appears I need to do it again, as they are all blurry.
The first thing I noticed when I removed the cover was the chain driving the main rollers has become loose and almost coming off the bottom sprocket.
I dont know much about this part of the mower, so I will get some more photos taken and post next weekend to get some expert advice.
Thanks in advance and cheers
Ian