My 67 FJ40 (F engine) has been running a bit rough lately. I checked the vacuum and am only getting around 15psi. Checked compression and all are around 130 to 135 except #5 with 120 psi. We did a leak-down check and could hear air pressure escaping out of the exhaust pipe. An aircraft mechanic friend told me they are able to reseat the valve sometimes by 'staking the valve' ie hitting the top of the valve with a hammer in the hopes that it may spring back in to place and seat. Has anyone ever tried this before? I'm getting tired of dropping money into this POS F engine. If the engine goes then the 3 spd and transfer case will also go.