Hi @Debdiver, thanks for your post.
With pulsing, it will be caused by a blockage in the machine or a dirty filter:
2. Can you please check the bin inlet ?
In the inlet the wand connects to the clear bin there is a tiny flap. Tilt the machine up and down while looking into the inlet. Does the inlet flap open and close freely? If it's stuck, please remove the bin and poke it with your finger until it moves freely.
This video can guide you in removing the bin:
3. Can you tell me when and how the filter was last cleaned?
4. Next, can you remove the filter entirely -
Then open the bin door, as if to empty the bin. Test. Does the machine still pulse?
If the issue continues, I do recommend reaching out to our online support team for further assistance to get your Dyson up and running again. Visit Dyson.com and click Support to get in touch with the right Dyson Customer Care team for your region.
We'll look forward to speaking with you!