Your best bet for recoating flyback tranny's would be sensor safe RTV silicone you can get at many auto parts stores,It does not use any acid that can possibly attack the insulation on the copper windings.Before you recoat the fly you should make sure you run the set for a few hours to get any moisture out of the fly so you arent simply sealing in moisture which could cause corrosion problems down the road.Also as for the fire issue maybe you could post a pic of the damage???You may want to inspect the yoke,for damage also as if the horizontal coils shorted then they can cause the fly to smoke.Also older flys were constructed with paper in between each layer of windings for the puropse of insulation and sealed with wax to keep moisture out.Unfortunately when the laquer insultion on the copper wire breaks down due to age or overheating becuase of poor ventilation or other external malfuntions arcing occurs causing heat and smoke and yes sometimes fire if the windings dont open.As a technician that works on modern sets flyback fires are rare but still have happened and in one instance in an older rca proj. set a fly actually detonated very violently and I also have seen where the epoxy breaks down and the fly arcs the the output transistor which is usually located close to the fly in modern sets which usually melts the case.