Took mower deck off the blue 123 and found my hy-tran leak. It is the tube going into the transmission case. Part number IH-394827-R21. I tried to tighten the 1" nut but was turning harder than I thought I should and quit. Is there just an o-ring that failed or am I forced to replace the whole tube? The replacements don't look like the original. What's the deal with that?