MicroMate: SDHC cards not recognised

Recently, my MicroMate adaptor (for SD-SDHC) has stopped recognising a number of my SDHC cards, including SanDisk and Lexar. It still recognises an older SanDisk Ultra II card.

Switching from MacBook to iMac Intel (both OS 10.6) to iMac PowerPC (OS 10.5) makes no difference.

Works OK when I connect the cameras with a USB cable but the MicroMate is so cute and easy to carry around in the little pouch with the M2 phone card adaptor.

Any suggestions - maybe time for a new Mate?