rpm sensor - low rpm cutout

[quik550]

I rarely ask a question here as I am a mechanical moron. However, if the advice is good, it could help me ask the right questions of the trained person.
I have a Euro 3.2 with a Euro brainbox. The engine is fresh and runs well, except it was hitting the rev limiter at 5600 rpms, ruining my fun. I borrowed an Autothority performance chip and it cut out at about 6100 rpms, so I ordered a custom Steve Wong chip. The low end increase was noticable, but it cut out at 5900 rpms. I spoke with Steve and he tells me it is likely a faulty rpm sensor (either too close to the flywheel, a short in it or a bad sensor). Does anyone know how I can test this? I might need pictures to understand as I am truly mechanically challenged. Thanks in advance to anyone who can help/van

[ZOA NOM]

These might help:

[quik550]

Thank you so much. I almost understand this explanation and I have printed out the response you sent me. I will take it with me tomorrow when I go talki to someone knowlegeable. Maybe I will see the track this year. I gave up a free day today, but there is always next week! Thanks again/van