WELCOME to these Forums....
Heat will "Burn" hydro oils... Even a good synthetic, if you heat it often enough and Hot enough will burn...
at 300 hrs you should have had at least one hydraulic fluid & filter change, each side holds 2 gallons of 20W50 (synthetic) engine oil.
Metal shavings had to come from something that generated a bit of heat... A rebuild is possible But there will be a Lot of damage inside, You may be better considering replacing the complete drive... :smile:KennyV