Check the spindle bearings for wobble too. You might be able to adjust the pre-load on the spindle bearings (by taking the quill out) to improve matters. Fitting new bearings is not an expensive job - just needs care and cleanliness. Don't buy the bearing as spare from Meddings but use the many online suppliers for a fraction of the price. If the belt does not relax to a near perfect circle when taken off and laid on a table, treat it to a new one of the cogged type (google for pictures) again not dear from bearing suppliers and the like.
The worst situation will be if the machine does not have a removable arbour and the spindle end is bent. Virtually impossible to straighten and you will need a new one from meddings. They still support most of their drills with parts at a price.
If the arbour is removable* but bent, then they too are cheap enough and use standard tapers. One to fit in the chuck -JT6 is the commonest on British drills with 1/2" chucks nd the other end to fit the drill - MT2 again being the commonest.
* for the arbour to be removable, lower the quill and there will be a slot to insert an ejection wedge. If there is no slot then you don't have a machine with a removable arbour. and you need a pair of metal folding wedges sold for the purpose, to remove the chuck.
see
http://www.google.co.uk/?gws_rd=ssl#saf ... val+wedges