You have what is a common problem on most of the Mitsubishi sets made at this time. CONVERGENCE.
This model uses two of the STK-392-570 convergence chips and if set will not adjust both have to be replaced.
You have some options here:
1. You can have a shop do the repair--average seems to be now about 250 parts and labor.
2. You can buy one of the kits available with general instructions online for around 100 dollars with most of the things you will need.
3. I have start to finish, step by step instructions (based on doing this repair in your set hundreds of times) for free--provide a email address for this.
In general the middle board has to be carefully removed as all the parts for this are on that board.
Soldering is needed as each chip has about 18 pins.
You can get a pair of the chips at for example AT Suburban Electronics for under 20 dollars including shipping. They also have some of the other things you might need that are listed with my instructions.
There are 3 different ways to get at the parts:
Remove the middle board which is what I do.
Remove the entire light box in the set---harder.
Unbolt and tilt entire chassis up so bottom of the boards face rear of set--hardest and allows possible damage to happen.
parts look like this but are 570 and number is on front. They face the front of the set and are bolted to the very large metal heat sink with fins there.
Let me know if need my help.