I had a go at this with my inexpensive noname soprano and I failed quite miserably . Well, I managed to lower the action at both the nut and saddle without many issues but intonation is still crap (on the low side on all strings at 12th fret). I also overdid it on the C-string at the nut, which yielded me a buzz.Seeing as it is an inexpensive ukulele if you have ever built a model or put on makeup you likely have the dexterity to pull off your own setup.
https://www.youtube.com/watch?v=Zbp7dApxAuE Diagnosis
https://www.youtube.com/watch?v=SGGz14ohX9Y Repair
Check out those two videos and decide if you want to try fixing things yourself. Their is another guy fixing a blue malhalo but his idea of popping the nut off to file from the bottom does not sit well with me. I use cheap files from the local Harbor Freight straight from China. Wasn't too hard to find a few with the shapes needed.
~Good Luck~
Oh well, a good learning experience anyway!
Any ideas why the intonation is still bad? The saddle is even and string height at 12th fret is now just under 3mm, and the strings lowered at nut to just a paper between strings and second fret when pushed down at third (save the C-string that I screwed up).
PS. I built a lot of models growing up and am quite handy overall. Experience is the key here I think, and for that you need to try it out a few times. DS