My 128 won't go into 64 mode.

[128user]

I have a flat 128 that I got on ebay several years ago. I use Wheels 128 mostly as a replacement for GEOS.  Recently I can't get it to go into 64 mode.  I have a few games that I use that mode for.  Does anyone know what the problem could be.  Thanks for your help.

128user

[LokalHorst]

the description is a bit thin -
what do you get after Go64 or power-cycle/reset with held-down CBM-key ? (blank screen, blue screen, weird charset chaos)
Any modules in the catridge-port ? (if so, remove them temporary)
Maybe reseat the ROM's (U32,U33) by lifting them up slightly and pressing them firmly into the socket again.