I've never seen a bent lifter. If you have a soft faced hammer give each of the valve tips a wrap with the hammer. The valve should move. If not you will notice if you have a stuck valve.
The clean gas is washing the varnish out of the tank and giving you problems. If you can find a radiator shop that still has a hot tank you can maybe get it done, ask a price first. It may be cheaper in the long run to buy a new tank.