Lpc2000

I am using the secondary JTAG port to debug my target (LPC2106 Target;
Nohau Debugger)  Initially, I flashed the part through the serial port
using ISP, loading some code that enabled the secondary JTAG port, then
started using the secondary port.  Sometimes this port works, sometimes
it doesn't, and this state seems to be 'sticky' in that it persists
beyond reset and power cycling.  I've read through a couple of threads
here on the subject, and see some mention that there may be a design
flaw in the secondary JTAG port.  I can find no mention of this beyond
this group, though.

SO..

1. Is there a flaw with this port that makes it unreliable in some way?

2. Is there more information beyond AN10255 that discusses how to use
the secondary JTAG port?

3. Are there limitations to the use of the secondary JTAG port?

Any help would be greatly appreciated.

Thanks,

James Dabbs, TGA