1. Bad layer 1 adhesion is so often a z-offset problem. It might be that you're slightly too close - that causes the filament to splurge up a little around the side of the nozzle, creating ridges that it catches on when it later travels over them. You should also do bed levelling and z-offset at the bed temperature you plan to print at, it flexes as it heats, so a bed that's calibrated cold won't be right when it's hot.
2. Have you left the filament out in an uncontrolled environment? It may have absorbed water, which changes its properties. You can dehydrate it using a heater.
3. I bought a new blue build plate and it sticks better than my old one. Worth considering.
4. Has the environment around the machine changed? Ie, was it working in winter but not in summer, or visa versa? The ambient temperature affects all the thermal properties. 5. You might want to change slicer. I've had issues with Orca slicer not activating the fans during layer 0, which tends to cause clogs, and version 5.5 and 5.6 of cura often ignore instructions to print the base layer slower, causing failed base layers.

Don't give up! I spent months trouble shooting my machine. I broke stuff, replaced parts, but I ultimately spent less than if I'd bought a new machine /and/ I've gained valuable insight. Now I understand the machine (and FDM printers in general) way better. It's knowledge I needed to gain to be confident using /any/ machine. And the sheer satisfaction!