Lots of good suggestions, but maybe try a simple one as well? By hand and with a small pull, you should be able to determine if the rig is tensioned close to the same side to side. That does not tell you about mast centering, rake, being in column, perfectly correct tension and so on - but if it were rig tension side to side causing port/stbd differences - the simple test should tell. With some practice on other, similar, boats, you should be able to tell if your rig tension is close to 'right' as well.
The other balance and mast check suggested are good ideas as well, as is having the rig properly tuned. But, you should be able to check for large rig tensioning problems with your hand and a pull on the wires.
OC
The other balance and mast check suggested are good ideas as well, as is having the rig properly tuned. But, you should be able to check for large rig tensioning problems with your hand and a pull on the wires.
OC