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I viewed your photo saw the dripping fuel but couldn't identify exactly where leak originated. If leak is between top cover & pump housing then that gasket cam be replace with pump remaining on tractor. One needs to pay special attention to where spring under the cover is attached. How many hours are showing on speed-hour meter? It's possible check valve that fuel return line attaches to on IP is clogged causing gasket to leak. If check valve is clogged drive ring inside IP is more than likely failing.
Caution: one needs to utilize extreme caution putting fingers close to leaking inj lines or hyd hoses as either liquid can be forced under skin requiring SERIOUS MEDICAL attention