air bleed screw frozen in filler cap

[SongWright]

As a new owner of a Forty Featherweight circa 1982, I am proud to have revived it to running order. But I have been unable to loosen the air bleed screw in the fuel tank filler cap. The screw seems to be made of aluminum, and the cap of a composite material (Bakelite?). I am afraid to apply too much torque lest I break it. Other than that it works great! Any suggestions?

[Hugz]

Use mulitigrips... it won't break.

[RickUK]

Only problem with Multigrips and the like are that they chew up the knurling on the screwhead. If already abused,then it probably doesn't matter, but if in a fairly good condition, try nipping the head between two pieces of wood in a vice and gently rock the cap in both directions and start to free it up - chances are it has only just nipped up - the screw is aluminium into a brass threaded boss.
The thread is generally not a tight fit compared to other threads around a Seagull, so you might have a chance to get some WD 40 or similar to penetrate the thread from the underside of the cap.
Once you get it moving use some light oil to lubricate the thread and the washer under the screw head.
In use, there is no need to crush tighten the screw - just enough to close the air vent.

[jimbo2107]

try pouring boiling water on the main cap area, they have different expansion rates.