Random cranking issue, M57 diesel 2003

[jonbmw]

Hello

I'm having a issue with my 2003 3.0d (520k km, 320k miles).
This issue has been appearing for about 2 years, on and off, but has recently started happening a lot more frequently.

Issue is with starting the car. When starting to crank the car, it sometimes cranks a few times and then suddenly stops, makes kind of hissing noise from the engine. Then i can crank again and start the engine. But depending on the car's mood, i might have to do it a few times to start it. This happens about 50% of the time now. I'm suspecting a starter issue, since the engine works and starts fine when this problem does not happen.

Does anyone have any clues as what might be causing this? I have not pulled any codes yet, but since this issue has been going on for a while, the car has been to the shop and i've read codes myself a year ago, but there wasn't anything wrong. One shop I went to last year for suspension work, said the starter needs replacing, but i would like to be sure before i spend cash on that.