Thanks for all the different advice lads, i have managed to remove late last night. I froze the yoke, stem and then put in the vice and then heated the bearing localy and managed to get a screw driver knocked in at the bottom of the bearing and prized up enough to get two thicker screw drivers either side and prized right off and it came off quite easy. I then put the new bottom one on by putting the whole thing back in the headstock and with the old top bearing in place with a washer on top then put the top plate back on and pressed the bottom one on to the spindle by tightening the top nut and it worked a treat. I know it sounds bodgy but it worked quite well.