I am having difficulty pulling the blanking plug to replace the flywheel after going back in the water this spring. I'm not sure how much effort is safe to apply or if I can try to gently twist it with a wrench to get it loosened
Welcome to the Raymarine Forum Pweiner106,
The transducer insert as well as the blanking plug are designed to be extracted from the transducer housing by lifting straight up on the insert or blanking plug after fully unscrewing the locking collar. As the transducer insert and blanking plug are indexed, it is not recommended that a transducer insert or blanking plug be rotated. As these transducers, are manufactured for Raymarine by Airmar, Inc. you may want to consider contacting
Gemeco, Inc. (Airmar’s US distributor (803 693 0777)) or
Airmar, Inc. ((603) 673-9570) for additional tips which may help with a removal of a transducer insert or blanking plug.