Ref. My last posting .. after taking the replacement mechanism (bought off a scrappy) I cleaned both spindles, one of which was semi-seized, and fitted it only to find that the arms would not sweep correctly ... After much cursing and adjusting the motor arm settings we decided to take it back out and fit the spindles into the original mechanism ... To cut a long story short this worked!!! I now have working wipers just in time as the weather is on the change.
Just to inform anyone with a mk2 2.8v6 Galaxy ... There are two types of mechanisms so make sure you order the right one .. They are both very similar (as I've found out) but the spindle arm was longer on the 'incorrect' one hence the sweep only did 75% on one arm (my son cut it to the same size and welded it and now everything works perfectly).
Moral of this story ... DON'T over tighten the nuts holding the arms onto the spindles as the thread will snap off, this leads to replacing the spindles and, as you can't buy them separately, you'll need to buy a mechanism in order to swap over the spindles ( please clean and lube these first of all) ... And be prepared for bruised knuckles!!
Btw ... Anyone want to buy a wiper mechanism with only one good spindle ... Works perfectly but not in my V6 Galaxy

AND a big thank you for those diagrams showing the positioning of the linkage arms etc etc ... invaluable assistance!!