JD 7520 Transmission Overheating Update

I took the transmission cover off today to take a look inside. The gears looked good for the most part. I found a couple chipped edges and the reverse was worn where the coupler goes but for the age I thought it looked normal. I did find a broken bolt, part number 19H1944 in the lookup. It looks like this bolt acts as a stop for the shifter. This was broken off allowing the shifter part number AR73158 slide back too far and rub against the side of a gear on the back right hand side of the transmission. There is a place worn on the shifter but nothing major. Does this seem like it could cause the heat I was seeing? I attached a hose to the oil return so it wouldn't spray and watched it while I ran the tractor and there is oil flowing when the clutch is released when the clutch is depressed the flow is quite a bit less. This return line from the pump to the transmission cover has a dent that I would guess reduces the size by about half where it clamps to the frame by the engine, would this be the cause of the chattering noise I explained earlier? The chattering is just on that line. Watching it while it ran it would come out more in spurts then a good flow.
Thanks

I forgot to mention I also drained the fluid and pulled the screen which didn't show metal filings. I then used a magnet to fish inside and found some metal filings but nothing large. I also can't find the rest of the bolt! Should I put a big magnet on the bottom to the transmission?
Thanks

Unfortunately you can"t see much like that the gaulding usually is under a pinion to the shaft, or a bearing seizing...Darn it...