Same thing happened to me yesterday. I got the tractor out of the shop to remove the MMM and install the FEL and the rock shafts would not go down.
They would go down VERY slowly, about 6 inches in 15 minutes. Even with the bush hog on the back, it would not go down proper.
I had not messed with the drop rate valve under the seat but somehow it got turn back to almost shut. Brain fart on my part.
I forgot about the drop valve at first so I came back inside and re-read this post, adjusted the drop valve and all was well.