42S display lense fixer upper?

[Matt Agajanian]

(07-09-2017 02:07 AM)Dave Shaffer Wrote:  Be a little careful where you use that "air." It may well have some (oily) impurities - DO NOT USE IT, for instance, to clean the sensor in a digital camera.

To avoid that mishap, how do I check if the contents have impurities?

Thanks.