Two possibilities Ralph. You have been running it too easy and slobbering unburned fuel, or you have an injector pintle not seating properly. Need to take it out and give it a good workout for half a day. Of course that manifold gasket ring is leaking so looks like only this cylindar is leaking. Replacing manifold gaskets is an easy job on this tractor.
Does it miss and sputter when starting when cold then catch on all 4 after a few seconds? Would indicate a dirty injector.
Gene