The Knack can be good and bad. Everyone will want you to fix their stuff and for free. Somehow they know you have it. Good part, $8 in caps got a $450 monitor for my son a couple months ago.
The knack can eat up your time too. A neighbor saw me out last night, said my AC will not go over 32. I said you probably flipped the thermostat to centigrade. After a blank stare, I went in his house, flipped a switch and hit the reset button. No idea who opened it and flipped the switch but he has teenage kids.