Thank you for your posts.
Right, found some time to re-read your posts, grab the spanners and have a go!
Started by confirming there is plenty of fuel entering the carb.
Started dismantling the carb. Took air filter and filter holder off.
So looks like this:
At which point I fired her up to see if fault persisted. At which point she ran a lot better!
I couldn't understand what difference it made. So reassembled and tried again and still works OK.
I know it would be best at some point to clean out carb properly but would like to get the field cut first, as the grass jus keeps a growing!
At hi revs she sounds OK. At lo revs she does do 'something'.
This is a Hi revs video:
https://www.youtube.com/watch?v=RJemiLKWm3k
This is a lo revs video:
https://www.youtube.com/watch?v=htbAhu2OtJY
In the lo revs video, look at what happens about 3secs in. You can see it again later in the video, is zoomed in. Is this normal?
Seems like a lot of fuel is suddenly spurted out and the engine sound changes a little.
Let me know your thoughts, thanks in advance.