I phoned the oyster helpline and yes you will have a problem with the
negative balance. You will have to rely on the Bus Driver using common
sense.
I was told a member of staff tried to use thier staff pass and as it did not
work the sensor they were ask to leave the bus.

Record card or no record card just go to a ticket office and ask for a print
out from the machine. It will have all the relevent details.