How do you fix a click torque wrench?

If you have a "click" type TW that is not torquing the advertised value, often times you can disassemble, clean, lube (with a really good grease like that peanut butter looking stuff) and finally adjust it back into specs. Of course, to adjust it you would need the test equipment to do it so this is usually done at a calibration lab. Whatever you do, DO NOT squirt oil inside the torque wrench hoping that will keep it accurate. When light machine oil and grease combine, it produces a varnish that builds up inside the TW changing the size of many internal parts by the build up of varnish thereby making the TW inaccurate and non linear. When that happens, the only solution is to completely disassemble it, clean, lube and usually some light to moderate sanding is required on key parts but you gotta know what to sand and what not to sand.

Most "click" type TW are micrometer adjust (twist the handle to select the desired torque) have a "pawl" in the internal guts that is really the heart of the TW accuracy. A "pawl" looks like a rectangular cube of very hard metal that looks like 4 of the sides are the same measurement. That is almost never true. 2 of the sides will be slightly shorter than the others but you cannot see the difference without measuring it with a micrometer. You don't sand the "pawl" but you usually have to sand what the "pawl" sits in between. If done correctly, this works amazingly well to bring a TW that was inaccurate and non linear back into specs with plenty of room to breathe.

Basically, if your worried your TW is not torquing correctly, send it off for repair/calibration. Snap-on Inc's lab will do it for around $25-$35. Also, do your self a favor, don't buy a TW based on which one is cheapest. You get what you pay for. I won't say which ones I don't like (and its a long list) but I will say the really good ones are SO, CDI and Blue point. And in case your wondering, yes, I work on TW's for a living. There's a lot of technique and practice to get good at fixing TW's and most days I still learn something new I haven't seen before. Fixing a TW is not something I would suggest to anyone who hasn't done it for a long time and if you have been doing this for a long time, you wouldn't need my input.