I am ubable to get reverse gear to fully engage on my 1981 Cat 30. The engine is Atomic 4 and it appears that a portion of the engine block is stopping it from going completely into reverse. I still have reverse but it is not 100%. I can tell it is not correct by the reduced rotation speed, higher pitched noise coming from the gear box and unclean shifting when moving to reverse. Any help or ideas are appreciated. Thankyou.