[SiriusHardware]

By all means send the IC back again but, since it has shown very different behaviour on two occasions in your own machine I'm not sure what conclusion we could draw whether we find it still does or does not slow down the operation of the uploader on my machine. Maybe there was just some very persistent oxidisation on the pins which has taken a few insertions and removals to scrub off.

I meant to do the VDU check just about now but have just discovered that one of the ceramic capacitors has been knocked off - fortunately, I found it in the drawer where the PCB itself has been living for many years. I'll take it to work, where I have much better light, space and soldering / desoldering tools than I have here nowadays. I'd better keep the whole thing in a padded bag from now on.

The test will not be a true test, in the sense that my PIC 'VDU Demo' board will be driving it, and the port pins on that have very different (stronger) drive capability than anything on the MK14's buses. But it will be running at full (4MHz) speed.