Strange artifacts when using Solidify I am pretty new to Blender, and have run into a problem that's been bugging me for days now, and I can't seem to find any solution in the forums.
Basically, I'm trying to fabricate a vacuum manifold with a weird shape and ideally a constant 3mm thickness.  Here is one-half of the object without any thickness (I haven't applied the Solidify modifier yet):

Everything looks hunky-dory when it's just a 2D mesh, but once I try to add a Solidify modifier, I get very strange artifacts in two small strips on the cylindrical end:

I've tried using the wireframe view to see if there are any errant vertices or edges, but all I can see are these weird curvy edges (in the vicinity of the deformations) that I can't seem to select or delete like normal edges between vertices.  These weird, un-selectable edges seem to disappear when I remove the Solidify modifier and go back to a 2D mesh.
As long as I'm here, I'd also be extra-grateful if anyone can tell me how to make the thickened edges of the 3D part align so they're flush with the YZ-plane (since I plan on 3D printing this part and its YZ mirror-image and epoxying them together to create the complete vacuum manifold!).
I'll attempt to add my &quot;.blend&quot; file to this post.  I am very new and clueless with Blender and I'll bet I'm missing some basic concept ... literally any advice would be very much appreciated!
Thanks in advance.
There is a vertex mishmash. Press M to Merge by Distance with value like 0,001

I did some more manual cleaning (Merge by Last to merge some others vertices that were close to each other) and Slide by Edge GG to straight back some edges of cylinder part.

To keep straight cut in some axis I would suggest to use Mirror modifier and as final touch apply Solidify and Mirror and use Bisect tool to cut.
Topology is not good, so if you will have more issues, you would have to retopology your object anyway.