Agilent 4155B error

[chilternview]

Anyone seen this? My newly acquired 4155B fails on power on self test, maybe once every 3 power cycles with an error 10907 which I gather from the docs means  " Integrating type AD converter failed calibration or self-test. "

The only workaround at the moment is to power down, wait a minute then power on again. But that may not work forever...