The first layers are ticking

My first thought is an uneven bed that is too close to the extruder. But I am pretty sure the bed is not flat. There is a low spot right in the middle. If I raise up the extruder any more the plastic will not adhere in the middle. With medium to large prints this happens on both sides of the bed. The extruder gets too close to the bed and prevents plastic from coming out. The stepper makes a ticking sound when this happens.


Maybe you guys could not understand my post... I dont know. But I have helped this problem by increasing the temperature for the first few layers(using black PLA from filament outlet). And lowering the extrusion multiplier by 2%. It still happens just a little bit though.
At first this seems like a bed level issue but the strange thing about your photo is that the outside loop looks OK. If the bed was low on that side, the whole thing might not stick. Is that part of the acrylic sanded, which will allow the PLA to stick better? One idea might be to throw some glue stick on to part that does not stick well. That will raise the level of the bed slightly and give the PLA something additional to adhere to. I know this would work with a glass bed, which is what I'm using, but don't know if glue stick works for PLA on acrylic.