The following is a write-up that Steve Honour placed on the Cruising World Bulletin Board with regards to tuning a ketch rig. I have shamelessly copied it, I am giving him the full attributes and am reprinting it here!! I added a couple of clarification sentences to his description but have not changed the methodology. You might want to follow his method if your removed and the reinstalled the mizzen mast once the mast is back up. See "Drop the Mizzen" for instructions on that topic

If the boat has not been tuned for a few years, it might be a good idea. Regardless of how your rigging is set up, some basics exist:

1. With all sails up, in light air, there should be no lee helm. The masts should be centered left and right.
2. If there was no lee helm before, and the mizzen has not moved, then it is a good assumption that the rake (whether they lean foreward or aft) of the masts was proper. If you now have a lee helm, then the mainmast must have moved aft a bit.
3. Does the main mast have backstays? Loosen them and the aft lowers until the triatic is once again taught. Take up the slack with the forestay.
4. Now, before you mess with the lowers it is a good time to check the uppers.
5. Easy: take the main halyard and bring it down to the chainplate on each side. It should come to the same place. If it appears longer on one side, then ease the upper on that side. If the main backstays are double, as most ketches, you will also have to ease the one on the same side.
6. Once you have the top of the mast centered, check the column by sighting up the groove. center the middle under the top by adjusting the lowers. If you have double spreaders, you're screwed. (just kidding) simply adjust them as you would the lowers to affect the upper spreader to mast junction.
7. Do the same with the mizzen. Take up any slack in floppy stays.
8. Now go sailing upwind in about 12 knots! (my favorite part)
9. Sight the mast up the groove. a gentle bend to leeward at the top is OK, but you can make it straight by easing intermediates and lowers on the windward side if desired. Don't touch the uppers.
10. Now go to the leeward side. If the leeward side is real floppy, count the turns to take all the slack out of all the shrouds (including the back stays then back off half that amount, tack and tighten the other side the same amount. Check the column again on the new tack. You may want to ease the lowers or intermediates to get it straight.
11. Tack back and check the column on the first side again. You may want to ease the intermediates and lowers a bit to get it straight. I find that the uppers need to be the tightest and the lowers the loosest because the uppers are longer and stretch more when loaded.
12. Do the same for the mizzen mast.

Now you're a seat of the pants rigger!

*smile*

Regards,

Steve Honour

ps... if ya don't want to go thru all that, just ease the lowers and backstays enough to allow the main mast to move forward, this will take the slack out of the triadic when the forestays are taken up a bit. Then snug up the backstays and aft lowers. Always count the turns so you can do the same amount on each side in or out. In the case where the mizzen mast was lowered and the main mast was not touched, then snug up the shrouds on the mizzen. If it was straight before, it will still be.