How to dim a 12vac wall wart for a halogen lamp?

I need to replace a fried 12vac 60W foot slide dimmer (KAOIY #KFT-6022) for a halogen lamp. This lamp has 2 35W bulbs. Is this why the dimmer fried or is that within useable range? I can't find a replacement without ordering 300 from China. One of my lamp parts suppliers has 60w 12vac wall wart it lists as dimmable. How would you dim this? I tried a Leviton 120V hi-lo line switch on the load side, it only worked on off. Could you use one of those table top dimmers on the line side, the kind that plug into the wall outlet and then you plug the lamp into it?

Thanks