450C Float function

I just had some work done on my 81 Deere 450C (6505) by a local mechanic, and he tells me that "float isn't working" and he couldn't find a rebuild kit for the 6way valve. I thought he did something to break it, but when I got the unit back today, it works the way I thought it always did. This is the only dozer I've ever operated, so I have nothing to compare it to.

If I elevate the blade, and move the lever to float, the blade does not fall (and the handle doesn't "sitck" in the float...

450C Float function

450C Float function