2004 torque converter

Hey guys --

Just picked up a 2004 with under 19K miles; everything is great, except it seems like the torque converter isn't locking up.

I've tried different speeds and flat roads, and it seems to have locked up once or twice, but over the course of 250 miles that's it.

I read in the Cherokee section there is a brake sensor that needs to be lined up with the brake pedal; I'll check that asap, but wanted to see about any other opinions.

Thanks in advance

Fred