Andrea If you have problems with an amplifier and you can not find the problem, we are offering all new customers a ten hour tryout of our digital fingerprinting system. If you would like you can send us the bad amplifier (or any other unit) and one good unit so we can fingerprint it and track down your faulty unit. We also offer a free fingerprinting service where we will come to a lab and sit down in front of any working unit and fingerprint every board , unit down to component level. All we ask is that the labs too far from Pittsburgh pay for travel expenses. Then with your system on file whenever a unit dies, you can ship it to us for repair. We feel that this service will save labs large amounts of money as the big companys only care about bottom lines and not the customers. Regards Michael S. Leary O'Hara Spectrometer Service 164 Glenfield Dr. Pittsburgh, PA 15235 412-798-9885 412-795-0797 Fax