@moore.jez I had the same problem with my Peavey. The previous owner left the strings tuned, but the truss rod not engaged for over a year in the garage. As a result, I couldn’t get the truss rod cranked down enough to lower the neck relief.
I used the advice from this forum, and straightened out the neck. She plays like a dream now.
This is the thread: Peavey Milestone Truss rod question
And in particular, @Korrigan 's comment: