Your piece is floatting in the space : put in middle of the grid better for eyes tranquility! :)
(and more easy for rotate it! )

Some lines are floating in the Space (object G) Kill it!

Some objects are Hidden ! So Unhide all ! Kill them

Line edges have not same color so surrely belong to some different objects!

Your vertical are not exactly equal between blocks or even in the same block!

200,0000003 against 200,0000000

Some curves are overlapsed

etc...

Seems better efficient to redraw your object...more and more you redraw it more and more you find tricks!
Draw Arc Cont between Lines
Extrude Line for make a surface
3 Quarter Arcs + NetworkWork for make surface
etc...

Select All and press TAB & Write ExplodeMove = you see what is not good! (like lines inside object alone in the space... ;)
etc...