That's a very odd frame rate. It seems to be a perversion of 24p :p
It looks like you're using DirectShowSource(***, fps=23.976, audio=false, convertfps=true), which should return a correct frame rate.
Clearly is isn't
A few options:
1) Remux M2TS to MKV first using eac3to, then load the MKV with DirectShowSource, DSS2 (I usually do this), or FFVideoSource
2) Keep the M2TS, but try using DSS2 or FFMS2
3) Tweak your DirectShow config to use different demuxer / decoder - one that will return the correct frame rate.
4) Add assumefps("ntsc_film") to your script.. this is risky though, because your audio could desync