I don´t think that its to complicated.
I opened up a few lenses and had never a Problem to put it back together.
Also, that thing is "Frankenstein" to me, i converted the Back to a Canon FD Mount.

That means, when i would send it to Leica, i would hear the screams from Wetzlar to my Home
And the Lens was so cheap, it doesnt pay off to send it to a repairplace; thats the reason why i wanna try it myself

Have a good one