The debate between the Dripless Seal and Packings has played out here before. We have had the dripless seal for 8 years and like it. The only issue we have had is our boat seems to pass some air bubbles under the hull when motoring into rough conditions. A couple of times the seal has run dry. When it does we hear it howl and it gets hot. I contacted PSS and they supplied (at no cost!) a new carbon bushing with the vent/bleed fitting. A hose above the waterline allows any air accumulated to vent.

When I did the original installation I drilled a "dimple" in the shaft at the location of one of the set screws. This is SOP for industrial applications where holding is critical. For the second screw I tightened it as much a possible then "staked" it by using a drift punch that fits down inside the hex socket at tapping with a hammer. This is repeated a few times until the screw no longer will turn. The goal is to deepen the bite of the cup-poing set screw.

When I took the set screw out it looked like this. The one of the left is new, the one on the right was the removed one. When I inspected the shaft there was only a slight mark showing. A quick pass with a scotch-brite pad and the mark all but disappeared. Obvisously the shaft material was harder than the set screw.

Being of a cautious nature I also added a stainless steel split collar as a backup when id did the original installation.

Some have advocated using a shaft zinc but I prefer something designed specifically for the job. Here is the catalog cut from McMaster.com. The 303 stainless is holding up well.