I just got an a155 fixed (which I can confirm is working properly on its own),
and carefully connected it to the a154 (from here http://img846.imageshack.us/img846/1517/a154a155connexion.jpg)

I get strange behaviour - it jumps around steps 1 and 2 twice then 7 and 8 twice. Both were bought on a trade forum, the a155 was cheap as it was broken and I just got it fixed, now I'm wondering if the a154 might be faulty too

Does this behaviour sound familiar to anyone

Thanks