On my L4060 with the medium loader I can't lift the loader after digging into the bottom of a pile of loose material (pea gravel recently). Need to back out from under the pile on top of the bucket a bit to lift. Mine will lift 1,890lbs or so + pallet forks (maybe 200lbs), which is somewhere around what its rates to, if I could remember what that was offhand. Plenty for as heaped as I can get anything in my bucket heaped as high as I can fill it, as long as there isnt a pile I'm digging in supporting even more than would fit in a heaped bucket.
Get a hydraulic pressure gauge rated to 3,000psi or so & a Quick Disconnect to fit somewhere. A rear remote is the easiest to plug into & see if you have one, if not a loader QD will work. Actuate the appropriate valve for a few seconds to see what it makes out at (don't hold it for to long, but you won't cause any issues unless you hold it for a while). I dont recall quite what mine, much less yours maxes out as according to the specs, but it will be pretty close to 2,500psi.
If it's off, you probably want to adjust it to the top end of the spec range. That usually involves adding some shim washers to the relief valve. I'd highly recommend getting a workshop manual. They are a couple hundred bucks from the dealer, or can often be found lurking around as .pdfs online if you look. Not cheap for the legitimate ones, but very worth it. Gives you all the details on adjusting the relief valve or pretty much anything you or your dealer would need to do to maintain or repair your machine.
