Hi Guys,

Finally got to the bottom of this problem. I did the following but it didn't help.

Fitted the small piece of capricorn tube and washer in to the hotend.
Replaced the wheels on the Y axis as they felt a bit rough.
Replaced the extrusion that the Y carriage runs on (it had a few dings in it).
Re-leveled the bed and did an e-step check.

It was when I was leveling the bed that I noticed the problem.

I have fitted a dual Z axis drive I made up myself which has a GT2 toothed belt drive from the original threaded rod to the second one on the other side. I noticed that the gap on the right side of the bed/nozzle was sometimes a bit bigger then the left. Because they are connected with the belt/pulleys they should always be the same. When I checked further I noticed that the top bearing support bracket on the left side was broken. This was allowing the threaded shaft to move. This was producing a temporary change to the horizontal level of the X axis extrusion which in turn led to the "blobs" on the print.
I assume it was worse on the round prints because the head is moving about more.

I clamped the bracket back in place and re-leveled the bed - spot on !!!

Tried a print and it's back to normal.

I'll now print a replacement and fit it.

Thanks for all the advice and help.

Cheers,

Andy