HOW TO CHANGE THE VENTURER PVS 1371 PORTABLE DVD...

Question

My mum has just been to Canada and brought back 2 venturer PVS 1371 portable dvd players, one for my daughter for our car & one for her own car. We have just realised that they are region 1 and obviously won't play our dvd's. How do i fix this prob? Have checked out loads of sites and this model is not listed on any of them. I really need some help, as these now can't be returned. What do i do? Please, please can someone help?

Thank you very much!!!