can you turn on some of the USB_DEBUG and other options (new kernel), boot it, sysctl -w the new debug things that appeared to at least 1, and plug in the cart, run "vmstat -u usbhist" and then put the output from it somewhere -- it will likely be large.
at least these i think, too: UHCI_DEBUG OHCI_DEBUG EHCI_DEBUG XHCI_DEBUG UHUB_DEBUG UMASS_DEBUG UGEN_DEBUG the default history is 50k entries, so it should be more than enough, but if not, USBHIST_SIZE can increase or decrease it. .mrg.
