When mine makes a noise like that, if I lower the 3 point, the noise goes away at least temporarily, it is due to the filter for the hydraulic system needing cleaned out. It is on the right side of the tractor, most of the way back on the engine, there is a 2 bolt cover over the filter. You put a pan under the filter housing, remove the bolts, work the cover off being careful not to hurt the sealing O ring. Then pull the stainless steel filter out and wash out good in solvent, there will be lots of little metal particles in it, blow it out/off with compressed air, reinstall it, and the cap & bolts. Run then check the hydraulic fluid level. If the fluid is low, it may do the same thing. Not sure if this is your noise or not, but mine does this every couple of years. Hope this helps.
