Richard. Both top and bottom bushes have the same external diameter, the slider is a plain tube, so if the top bush comes out, the bottom should follow easily. Have a look down inside the slider, I have had them where someone has replaced the "Y" type mudguard bracket studs and they have been screwed into the bore. To endorse RD, check the leg for distortion. As to getting it out, a good dose of WD and working the slider on the leg as suggested should do the trick. No vice? Hooligans method would be to replace in the yokes without the spring, this will hold it still. If it is determined to stay in, then a bit of violence and perhaps the hot air gun should do it if no other obstruction is seen. The slider should pull straight off.
Bottom bush is held in place with a stepped nut and washer. Expect damage to the bottom bush, the problem could be grit trapped between bush and slider. Clean out and inspect the slider, and short term if the bush is reasonable I would use it and reassemble to be sure you have solved the issue before spending more. The leg can be checked for bending or bowing by rolling on a flat surface. Fork nut and yoke tightening sequence are outlined in the service sheets, available on the Forum in the literature section.
Swarfy.
