Terminal noises from fridge compressor?

What goes on inside a fridge compressor please?
Took my fitted 5 year old Neff one out today as the "clunk clunk" noise as it switches off is driving me mad!
When it started a year ago I thought the compressor was on the way out, bit a year late it still plods on.
Running it in the open it was very obvious that the klonking noise as it switched off was indeed coming from inside the compressor, like a rotor arm or similar banging against the inside casing.
Tried to make sure the fridge is sitting level and all is secure, but makes very little difference. It still clunks
Is this fixable? Or terminal?
Any knowledge would be welcome thanks

The compressor is inside the black dome that you can see. the actual compressor sits on springs inside, and the clunk you hear is when the compressor stops under load, the springs are there to absorb the sudden stopping of the motor. I can only suggest that the springs are becoming worn or the compressor con rod bearing is failing. The compressor could run for years yet, I've worked on ones that knock all the time.

hope this helps

Many thanks racket
I assume therefore that I cn't get into the "dome" to investigate further?
(I was worried that may contain the gas; forgive my ignorance!)
Much appreciate the advice

That's right you can't get into the dome it's hermetically sealed and there is also gas in there. Either you live with the noise or get a new compressor or better still a new fridge

see ya

Thanks again racket; very much appreciated
You may have just saved me from blowing somethingup!