Replacement pen-probe for Kee gold tester

Summary Replacement pen-probe for KEE gold tester (model M-509GM). Details When you calibrate a KEE tester, there eventually comes a time when you simply can't turn the calibration knob far enough to get the correct reading. This does not mean the tester is broken, it means you need a new pen-probe. A pen-probe is guaranteed for one month (see "Guarantee"). Guarantee Probes (pens) are guaranteed for one month.  A pen-probe is like a felt pen, if you don't replace the cap firmly it dries out. The manufacturers say it will give "up to a few thousand tests" (which could mean any number less than 1000). They also say it should be replaced after a year (a year from the date on its sticker). Although our survey (see comments from customers below) indicates that a pen-probe should last between 3 and 18 months, we know that some customers are still using them after 2 years; we know that some customers need a new probe after 6 weeks. Our guarantee is for one month from the date of purchase (invoice date) providing: it is still wet and not dried out. it is 'clean' and not dirty with contamination or squished out of shape (when testing, be gentle!) The guarantee is for one month, irrespective of its condition or how many times it has been used.  Comments from customers:  The KEE tests on average about 40 items a day and lasts about 6 months, 5000 tests. The solution in the probe outlasts the tip which becomes soiled from testing scrap. We replace the probe when reliability drifts and more regular calibration is required with our 18ct control sample. We get around 3 months and test around 10 times a day, often 15 times a day. Overall we think they last well.  Our probe only lasted 3 months, we are very disappointed. It's variable, some probes last approximately 12- 18 months each (about 2000 tests) and some  9 - 12 months (about 1000 tests).  The probes seem to last us at least a year, I would say that it was at least 200 individual tests, and perhaps even up to 400 tests over that period.  Sometimes a probe lasts a few months but sometimes only a few weeks. Shelf life v. Guarantee:  Although the manufacturers recommend you change it after a year, if it's still working, it's fine. Providing you are still able to calibrated the tester, you will get accurate results. We put a date (month/year) on each pen-probe. This is the date WE took delivery, it is to show when the pen-probe is getting to be a year old, it does not affect the guarantee which is a month from the date YOU purchased it.