It is a eldorado u-max Tabman,I sent in to have everything checked and tuned up,also replace GB pot,center shaft on gb pot sloppy there for causes eratic threshold.Have been using manual gb detectors for quite some time and even though im new to tesoro and this machine, quite sure the pot is defective.Want the machine to operate as new also ,did talk to fellow at service and feel completely at ease ,except for anxiety naturally, LO L! I did tell them I didnt purchase new ,no prob. Very excited about this machine and even though have only got to use about 15 minutes believe I will be having for long time.However long it takes will be fine,for not going out much at all right now,ground so hard that you have to chip away, no digging. Believe today makes 32 days straight 100+ temperatures here in north central okla. Thanks all for your replies