Can some one please help me!

I have a Knuth vector 600 with Fanuc O-MD and I am having this alarm always while performing a tool change. As soon as the tool magazine is going back to rest position, the alarm pops up!!

I also have an alarm code 8 on the servo amplifier module, but after I switch it on and off for around 3 times, it goes away and comes on ready mode.

I've opened the servo amplifier and changed all the capacitors but still the same. The machine works ok with all the 3 axis but stops while making the tool change!!!!!