Printer Paper Jams & Feed Issues

I'm really struggling to solve my printer's problem (HP Color Laser 150nw). When I send something to print, the printer makes all the right noises, and the rollers start moving around, but it doesn't seem to pick up the paper. The rollers go through a couple of rotations, nothing comes out, it pauses then tries again. Same thing happens again, so the printer tries a third time. Then it gives up, and the attention light comes up and my print dialogue says there's a paper jam. There is never a jam. I have tried replacing the waste toner unit, as well as taking out all the cartridges/toners/imaging drum and cleaning the inside thoroughly. I have also cleaned the pick-up rollers. I have done all this twice. I have turned off and on again a million times and every time I try to print, the same thing happens. This was not a cheap home printer, and having purchased a new waste toner unit, as well as a couple of spare toner cartridges, I want to be able to fix this printer. I have only had this printer for two years and have only ever used genuine HP parts and cartridges for it. HP doesn't seem to offer service agents who can repair it in the UK. I have also tried the online diagnostic tool, but every time the HP Smart app finds my printer, I have to then register my product (done this 3 times), and then when I register my printer disappears from the app and I have to repeat the whole thing again. I'm at my wits end after spending a lot of time and some money on this. Please help.