DOH!!
i did something similar when trying to get the water temp sender out of the thermostat housing on my 280zx (in fact i make an utter f**k up of most DIY).
managed to get it out far enough to leak, but not far enough out to actually get it out of the housing. then, because all my ham fisted efforts had rounded off the hex nut, i couldn't get it to screw back in to the housing, so it was stuck half in and half out. result - couldn't drive car cos water p***ing out of thermo housing, no AA cover 'cos car was laid up for winter and hence no tax, so i had to pay for it to be brought in by the garage, and they had to drill the little b'std out of the housing and then also discovered that i'd stripped some of the inside thread on the thermo housing - i don't know how on earth that happened since the sender was either brass or copper and plenty soft enough for the hex head to round off, but it did. therefore, i also needed a new thermo housing which took a week to arrive.
total cost around £100