As usual Tesoro has a great service dept --- they got my Cortes working great --was bought used with no warranty -paid 90 bucks and they said they gave me a break on repair cost and i believe them they put several hours of repair to get it right !-previous owner said he bought it used from a dealer on this forum and had used it much just that it seemed to work fine and i am going to give him the benefit of the doubt this machine probably had several owners and ended up be traded to the dealer to which it probably seemed fine with a short air test ===-fact is most Tesoros are too easy to get into--- 4 screws , remove a allen screws from knobs and a small wrench to remove nut from the dashpots and your in --to have access tio the trimmers -Rusty said - my Cortes was all jacked(target id , notch , discrimation ) up by someone messing with the trim pots and attempt at "circuit board" work - --- the "someone" probably was making an attempt to ground balance or adjust target id --didnt go as planned (just a friction adjustment of trimmers really put the detector specs out ) and ditched it -------------odd situation was along the same time i bought another used Cortes for my 21 year son from another well know dealer and it seemed to have a intermediant short and target id was off -- i just packed it up and sent it back - still out the shipping and i want be buying any more used machines (reguardless of brand) that are not under warranty or dont have proof of being serviced or i really know the guy and trust -tired of taking the hit