Hi @rikur_ , the bearings are ceramic, and lubricated by the primary water itself. If you have bits of sludge/rust running around the system, that will accelerate wear, but at 10 years old, it’s doing ok. I personally far prefer the older selectable speed pumps over the newer variables, but of course they are less efficient (electrically) than the newer ones (albeit I don’t think that there’s a noticeable difference in running costs).
Initially though, I would check the orientation of the pump head; you ideally don’t want the head pointing upwards, as it can catch and hold any air passing through. With the pump running, I’d suggest loosening the silver bleed screw at the top; air can make them noisy. If air comes out, great. If it dribbles water, also good. If it squirts water, the bearings are worn. If it is suspect, I’d recommend getting an old-style head from eBay (
https://www.ebay.co.uk/itm/GRUNDFOS-15- ... 635-2958-0 ); you’re less likely to disturb stuff by isolating the pump, removing the 4no cap-head screws, and refitting the new head than by changing the pump in its entirety, and the bit that remains is a steel casting that will see us all out.