As far as I can recall, there was nothing about flushing write buffers in the
doc. I had for the 3min and maxine. However, it wouldn't surprise me a bit if
there was some trick required w.r.t. that wonderful I/O ASIC. I remember that
when I tried to do SCSI DMA properly through it, it would run for a while and
then wedge such that only a power cycle would get the DMA engine in it working
again and I never was able to find out why. (The doc. I had didn't differentiate
between the I/O ASIC used on maxine and the 3max+, so you might try the same
trick that is used on the 5k/240.)

Good luck with it, rick