Hi,
If you can't adjust the convergence in all directions for all colours, then you need to replace your convergence ICs (integrated circuits). This can cost $300 - 400 to have the work done professionally, however it is possible to buy a self-repair kit. The kit for your TV can be bought here:
http://www.tvrepairkits.com/xcart/home.php?cat=3988
This kit costs
$69.99 and includes a step-by-step photo instruction guide and the supplier states: "
You do not need to have any prior electronic repair experience to use this kit."
This kit includes everything you need to complete the self repair including details of how to dis-assemble the TV, locate the convergence ICs and adjust the convergence following installation.
De-soldering of the original ICs is required and soldering in of the new ones, however they also provide instructions on soldering and offer email, phone or live chat support to assist you in completing the repair.
Many people have bought these kits and fitted them sucessfully saving themselves several hundred dollars. If you buy one, I would advise a little soldering practice before tackling your TV.
Hope this helps.
Regards,
BElectric