First thing to do is to check that your rig is installed in the boat correctly. To do this, carry out the following procedures. Slacken off any added back stay tension that has been applied so as to leave the rig as it is normally set up. Also it pays to remove your sail if you have roller reefing.
Taking a tape measure attach the end to the centre of the back edge of the forestay rigging screw where it attaches to the stem head fitting. Now measure to the front edge of the port and starboard cap shroud chain plates and make sure this measurement is the same. If it is not then take the shortest measurement and using a lead pencil place a mark on the deck on the longer side. Next measure across the boat gunwale to gunwale, with the tape going through these marks. This measurement when divided in half should equal the centerline of the mast. (If it is slightly out say up to 10 mm don't worry, but if it is more than this make a note in your log to move the mast step next time the mast is out for maintenance. This will slightly effect pointing on one tack to the other).
Climb up on the cabin and sight up the sail track. This should run in a straight line up the mast with no waves either sideway or fore'n'aft. Any sideways kinks can be taken out with adjustment to the lowers and then the cap shrouds. Remember half off one side, same amount on the other (always-small adjustments). A slight bend forward is ok but only slight as the backstay tensioner will take this out when it is applied.
Taking the spinnaker halyard and making sure it is clear from the block get one person to hold it to the pencil mark and so that the end of the snap shackle just touches the deck, have the second person tension up the halyard and cleat it off. Passing the spinnaker halyard around the front of the forestay check the fit to the other side. If it is out then adjust the cap shrouds until they are equal. The truck (top) of the mast will now be at 90 degrees to the deck.
If you have had to adjust the cap shrouds then re-sight up the sail track and adjust the lowers to get the mast straight again. Your mast will now be "in chord"
Remember that if your boat has heavy weather helm on the wind then the mast may have too much aft rake. This can be corrected by moving it forward (in chord) at the masthead. Too much weather helm means the rudder is at quite an angle to the centerline of the boat too try and keep on course. This angle has a marked breaking effect on boat speed and consequently the apparent wind and pointing ability as the boat moves forward.