Again fading print image left

[volkspost]

When my last color laser "died" after 10 years, I decided to buy a black and white laser, model HP LaserJet Pro M426fdw. I ordered it from Amazon on 17.07.2017. After about one year the print image on the left edge began to fade massively and was no longer readable. I decided to have bought a Mondays device and disposed the device, bought the identical device from Amazon on 12.11.2018. The problem started again two weeks ago, the fading is clearly visible on the left margin. When printing, scaning/printing or copying.
The original toner is at 80%, I tried the trick "shake toner cartridge" again. The firmware is currently at 20180201, it can't be updated. Test print etc. is also tried.
As expected, Amazon does not offer a take-back/replacement service.

On your website I read that the warranty is only one year, that would be really bad.
I don’t know if there is any help possible. For sure, if not it is „never again“.

Device: HP LaserJet Pro M426fdw
Product number: F6W15A
Serial number: [edited]
Manufactured: August 2018, Philippines

[Repairatrooper]

Have you tried another cartridge? Things happen and cartridges can fail regardless of toner level.

[volkspost]

Thanks for your quick answer. I don't like the idea too much. If this ain't work it is another + 100 Euro just for learning that it does not help. Tried this on my last one, same model, one more year ago.