I dont know if there is a check valve or not in the line, but I would not be afraid to run regular hose pressure to the line. The pex lines and fittings will take normal house pressure that is prob under 60 psi.
Sounds like the jet tip is, well, gunked up. I would try a little pure CLR pushed with some compressed air at 60 psi, leave the air line for an hour. If NO JOY maybe pull the air line and let the CLR sit may over night.
If NO JOY I would then try a tab bit of (eco) drain cleaner safe for plastics, pushed by a water hose, but this could be touchy if the drain cleaner gets on the gel coat exterior. Keep a second water hose ready for a rinse down.
Once it works again I would flush the lines and tanks.
L'IL Foot" 2014 Sunseeker 2300
"Harry" the JK toad in the mirror