If a screw gauge becomes stiff midway through or requires force to pass through, it cannot perform a proper inspection and should be discontinued.

Proper Use of Gauges and Reasons for Using Them 

JIS B 0251 stipulates that screw gauges should be used in a state where they can be easily screwed in by hand. When using a go-type plug gauge (GP), if it becomes stiff midway through or barely manages to pass through, it cannot be considered "easily." Measuring while feeling resistance midway through may lead to an inaccurate determination of whether the screw is within specifications.

Forcing the gauge in can damage it. 

Screw gauges are precision measuring tools and require proper force application. Forcing the gauge in when there are chips or burrs can cause it to snag and become damaged. Damage to the gauge can affect subsequent measurement accuracy and reliability, so caution is necessary.