Thanks for coming back.
I did the job this morning. Removal of the back was simple and the inside was amazingly clean given its seven years of use - no fluff and only light dust. The tube had a greasy black dirt on it; probably from the materials in the back and heat.
Adjustment was fun. Text is now much clearer on the right and slightly less so on the left, but overall much better. Interesting also is the picture appears clearer. However I did notice that on the white at the very edges of the screen there was a little distortion and the individual colours were visible as a band - probably morddwyd's description of convergence. Whether there is any mileage in attempting any other adjustment I'm not certain as the set is watchable and I'm no TV engineer!!
Thanks for your help.