A step forward – I have figured out whats wrong. I just have no idea how to fix it!
New chain ring is not sitting flush with the crankarm, leading it to sit far to close to the inner ring and causing the chain to catch.
On the old chainring, the bit of metal that surrounds the bolt hole is much thinner than on the new one. The new chainring can therefore not “sit” on the grooves in the crankarm. Should have notice it before, but you live and learn.
option1 – find out why what I thought was a straight replacement, is not in fact a straight replacement.
Option 2 – break out the dremel and make this bad boy fit.
Opinions?