I had a similar situation with my Travelpro when the handle stuck in the open position.

I removed it as suggested in the above post. The spring that holds the pin that goes in hole had become unattached from the handle button , leaving it permanantly in place.

I pushed in the pin, covered it with a small piece of plastic which I duct taped down, and the handle works perfectly.

Of course it is not 100% locked but I never had a problem with the results.