MGB? Pull the interior panel, remove the window "limit stop" and lower the window to allow access to the (hopefully) pop-rivets, drill 'em out and off it comes... and in the immortal words of the factory manuals: "Reassembly is the reverse proceedure of above." Be aware of the window lower track, as it can slip past the "nubbins" that travel in the slot when lowered too far.... and lube all moving bits while you're in there. It'll SCARE ya how easily the windows will go up 'n down after the job. /ubbthreads/images/graemlins/wink.gif
EDIT: White Lithium in an aerosol can is the "lube of preference" for the mechanisms. Silicone spray for the track felts.