Why would my sewing machine be making a thudding noise?

[u32ng]

I have a janome 525s. I don't use it very often in the grand scheme of things but I have done a few projects.

For a while I've been aware of it making a kind of thud/thump noise when I'm sewing. It's worse at higher speed and seems to happen on the downward travel of the needle. I'm pretty sure it didn't always make this noise but I can't figure out the problem.

I have:
Changed the needle not that long ago;
Unscrewed the base plate and brushed out bobbin/feed dogs as per instruction manual;
Checked the needle alignment.

I'm still fairly amateur though so maybe I'm missing something? Help would be much appreciated in case I'm damaging my machine!

Does it need oiling?

Get the manual out or download it then go through all the owner maintenance options. If that doesn't sort it get it serviced.

To keep a machine running well they really should be serviced at least every couple of years, even if you're not using them much.

Is it sewing nicely or is there problems with the stitch aswell?

is the needle fully in.sounds like it is hitting something on the down stroke?

OR ...it's not shifted position ..again clipping something on the way down?

Thanks I'll go and check if the needle is in fully.

Yes it seems to be sewing fine - no tangled threads or rubbish looking stitches.

The manual is pretty light on maintenance to be honest! I'm not sure that I am even able to get into it to oil it. Maybe servicing is the way to go next if the above methods don't work. I have had it about 3/4 yrs.