A few months ago I posted a theory about how to adjust the tensioner when removing the tensioner, (but not replacing it),as you might do when doing a new water pump or othe front engine repairs.

I decided that since the tensioner arrow did not come back fully to the end of the scale during removal I should mark that spot and re-assemble it starting at that point. Several people said that it would not work since the "book" MBCD says to start at one end of the scale and tighten to the end.

To make a long story shorter, It is working just fine... My theory of tension has worked out very good so far, 4K miles. No signs of any belt slippage with or without AC or steering loadings, etc.
If you are going to do your WP or dissemble the front cover and are planning to re-use your belt tensioner assembly you might want to re-read the posts I put up about how to tension the used units so as not to over-tighten them and shorten their life or other bearings, (Alt. and idler pulley and Water Pump, etc.)
If you use the standard instructions for installing a new tensioner you may have the whole thing under too much tension.

Admittedly a few months does not fully prove out a theory, but I did promise to report back to the group --- since several folks said I was in error.

Thanks for this great resource!

DanielW