Hello lobsterman! If you're still posting on TN, Brinkmann is still around. They make gas grills and other outdoor equipment but no longer manufacture the metal detectors at least in the handheld/hobby-type format as far as I know. Still a very capable, good machine if one is willing to learn how to set it up and use it properly and will oftentimes out-perform a good majority of modern detectors especially if the new ones are being used by careless and/or 'newbie' treasure hunters. I have this model and the next model up from it (the Sensor 5000) as well. The Sensor 4000 works (better) than the 5000. Possibly the best model Brinkmann made. Appx. 6 models were produced in the mid 70's to the early 80's. This one is from about 1980. Takes 8 AA batteries in two 4-battery, battery packs you can purchase new at some Radio Shacks or online. I had to get new battery packs for mine as the contacts were corroded beyond repair. I'd think anyone who services HAM radio equipment and/or CB radios could service this machine by the way. Not complicated to use or service at all by the way. Just a simple circuitboard with the pots and wires soldered to it. Very straightforward! To adjust the ground tune button, hold the coil above and parallel about 2 to 4" above the ground depending on how tall the grass and/or other obstructions below the coil are. Keep the detector from moving up and down and back and forth while slowly turning the large rotary knob counter-clockwise (until) right before you get a threshold hum. Your volume knob should be to the far right which is maximum. The top right knob is not really important as it is only for meter sensitivity and doesn't add to the depth of the detector. You are now ready to hunt. (If) you should (still) get a vague hum across the entire ground, then you need to turn your ground tune knob just a (little) to the clockwise direction but don't go too far to the right or you'll begin to lose depth. And remember, hunt as low to the surface with the coil as possible as that will improve your depth also. Ps. this machine does not discriminate but will normally (not) detect iron nails nor many other forms of iron trash either. When you find a target, you will be right on top of it and it will hum without having to slowly move the coil back and forth like a modern VLF slow-motion detector. That feature makes this a (GREAT) machine for pinpointing with. (this is a non-motion TR(transmit/receive) MD. Will pinpoint in normal search mode every bit as well as a modern handheld pinpointer by the way. Hope this helps you and if not you, than anyone else that has any question about this particular machine. HAPPY HUNTING...!
