I see what you're saying. I've operated his backhoe with a heavy rock and have had the machine want to lean way out there lifting the right side (if swinging to the left) up a little. But all you do is ignore it, becuase it won't go far, or if it's really bad, just raise the side you are swinging to the most. I just think, personally, that for an excavator, it's worth it to have a hyd. thumb, yeah you may displace some dirt with the thumb there, but think of all the advantages you have a hyd. thumb rather than a mechanical. There are many times when I wish the thumb on my boss's backhoe was hyd. just because of the freedom without the bucket controlling the thumb. Also, a lot of mechanical thumbs seem to be stiff, straight. A hyd. thumb is curved and that makes for nice fit on an object. My boss's is one of the few designed mechanical thumbs that is curved.
Blake
WA