<font color="blue"></font><font color="blue" class="small">( The draft links have pins with reversible inserts that either lock them to the risers or allow them to float several inches before making contact.)</font> </font>
Rick,
There is apparently something different with your lift links to draft links connection, as compared to mine. There are no reversible inserts for locking or floating on mine. So, I'm afraid I can't help you with that. It would help if you explained what model tractor you are dealing with and, if possible, post a picture or two of the reversable insert connections. It is likely that some one with knowledge of this style connection could be more helpful.
As for the float <font color="blue">("What good is this if the draft links lift right up?") </font>, I would guess that this would be useful for such as a rear mower, brush hog, rear mount snowblower... I run a front mount snow blower. When clearing, the SCV should be in the "float" position, allowing it to slide on it's skids while "floating" on an uneven surface. Similarly, it is best for a rear mount mower to have some "float" on other than perfectly flat lawns.
As for the box blade not digging in as it had before your long day's work with it, is it possible your toplink needs re-adjusting to set it back at the same level/angle it had been when you started? Is the lock nut on the toplink still tight? I'd check that all adjustments on the 3ph and any on the box blade, itself, are still snug and adjusted as they had been. I don't have a box blade. So, those with experience with them could jump in here and offer their expertise.
Good luck,
Tom