Leak from expansion tank

Hi,
I have a BM2 and earlier this year the pipe leading from the left hand side of the expansion tank down to the main tank developed a leak. I did not notice this until it had leaked all over the electronics and blew up one of the pcb's.The pipe is a fair bit rusty a tthe bottom where it meets the main tank. My heating engineer replaced a washer, and the pcb and it has been OK until now.

This morning I heard a noise as if the heating was coming on (when I did not have it timed to come on) I got up and noted water at the top of the main tank again and dripping down via the nice drain holes onto the electronics. I switched off, dryed and it all works again, but with this leak again.

Can you get a replacement pipe section/expansion tank or will the full setup need ditched?

thanks

Recheck / replace washers and use ptfe tape too.
Also you only need minimum water in header tank, due to expansion.
Mike

thanks wil give it a go