There's a certain way that the attachments are supposed to be put on. Not entirely sure, but I think the
PTO is supposed to be engaged when you bolt up the attachment. It could be that the clutch assembly is binding because the way the attachment was put on. If that's all it is, then you can unbolt the attachment and start again.
Second easy fix might be to lubricate the assembly on the top of the
PTO housing to be sure it isn't sticking.
If it get more complicated than 1 or 2, input from someone else with better ideas is needed.