Below level toilet.

I have a macerating toilet on the lower level (half way below ground level).
I know it's macerating, because when holding rank was full I could hear pumo running - plus I had to open the wall and saw all those pipes...
My question is: we have not used it for few months and now when flushing, water level comes up almost to the top of the toilet and drains slowly...
Haven't hear pump running either - so my guess is - tank is not full (yet).
What worries me is a slow drain - possible clog?
But I made sure no one flushes anything but bodily fluids and excrement plus toilet paper.
Can I deal with it myself or do I need to sell a kidney to hire a plumy?
Any advice would be appreciated.
Bonus question - how difficult it is to replace this kind of toilet dyi?
I consider myself fairly handy, but if pros are needed - I'll step back...