Easy solution
The best real-world working solvent for 5200 is gasoline. 5200 cannot be used on gasoline tanks since even when cured it will soften under the chemical combination. Stringy strands of half-dissolved 5200 in your fuel can be pretty rude to your engine.Patiently and carefully applied, gasoline will soften cured 5200 up enough that you can get a razor-blade or paint-scraper under it and prise it off. Be careful you don't mechanically damage the gelcoat.Chemically, the gasoline will not materially damage the gelcoat or fibreglass integrity if it is not left on long. Use a little at a time and wipe away all excess.And BTW-- don't do as my dad often did and keep a lit cigarette going during this sort of work!!!The gasoline is also the perfect thing for getting 5200 out from under your fingernails. How do deal with the gas-station-guy smell at the dinner table is another issue however!And yes, I would absolutely use 5200 for reapplication. It's the industry standard. Remember it's NOT a glue, it's a bedding compound; so however rigid it is when you torque up the bolts it will not get stiffer as the 5200 cures. In fact relying on the 5200 for primary adhesion of handrails and stanchions and sailing hardware will only invite flex leading to leaks and structural failure (usually of the deck).JC 2