Problem solved: Duhh. I did not know that the hydraulic oil reservoir for this loader is the hollow frame of the loader on the right side. When we added the bucket cylinders, it diverted too much of the oil so neither lift or bucket cylinders had enough oil. I had mistakenly filled only the hydraulic reservoir in the lower housing of the tractor itself. The specialist mechanic looked at the loader and the hoses and figured out where to add the oil. Then everything worked. We refilled the reservoir after flexing all the cylinders and now the loader works great.
Thanks for suggestions and this forum.