I am new to this forum. I just purchased a New Holland LX865 skid steer. According to the owner, the motor has recently been rebuilt. My mechanic thinks this is accurate. Supposedly, it has about 17 hours on the new motor. The machine has 3100 hours. It starts great. No blow by. Runs smooth, except for one thing I will mention. The hydraulics seem strong and responsive. I have a couple concerns and am hoping for some advice to get me heading in the right direction. 1) Between the motor and the "bell housing" on the right side, there is a pretty good gap--not quite, but almost 1/8". I checked the oil level in the bell housing/wingbox. It was a little low, so I topped it off. I am not detecting any fluid leaking out of this gap. My question is, why is there a gap? Is something out of alignment? Or is the gasket just really thick and perhaps the outside edge is missing? I tried to paste a photo of the gap, but cannot figure out how. 2) When you start up the machine, it fires right up. It idles smooth. If you give it throttle, it throttles up smooth to about 3/4 throttle. Then it develops a significant vibration with kind of a loud harmonic hum. If you throttle back down to 1/2 throttle, where it was previously smooth, the vibration and hum continue. If you throttle all the way down to idle it goes away. Then you can throttle back up to 1/2 and it remains smooth. Continue to throttle to 3/4 or full and the vibration and hum return. If you run and work the machine at 1/2 throttle it does fine, until you hit a bump or jar the machine, them it breaks into the vibration and hum and you have to throttle down to make it go away. It does have a hydraulic leak somewhere on the right hydraulic pump under the seat. When I got the machine, it was low. I filled to to the correct level and have cycled the boom up and down several times slowly and drove it slowly hoping to get any air out of the system. Any input would be very much appreciated. Thank you.