I recently purchased my first tractor, a CK25. It is a shuttle shift I beleive. I understood this to mean I must come to a stop before shifting between forward and reverse. I find it still makes a grinding noise sometimes, even if I let the rpm's come down to idle. It doesn't do it all the time and I have adjusted the free play in the clutch linkage to specs. Has anyone else had this problem or can you give me advice as to what I'm doing wrong?