After a couple of days I shaped the back and glued new nock pieces. Lower one is regular water buffalo and the upper one is cow horn from a shoe horn I found from flea market. After shaping the nocks I had not to do anything to the tiller but some 12 pounds has lost during the process. Sad for that but this will be the bow I´ll use in the future when my arms have lost their muscle power... or, perhaps, somebody is willing to buy it at good price...