Took my slr to a techy to get the trigger switch fixed and when i got it back i noticed the selector switch was no longer clicking into place for safe semi & auto (it was tight at first so i loosened the screw but still no click). Second problem i noticed it would have feeding issues like it would skip a gel or two before firing the next. What are the possible solutions for these problems? And are the problems related to each other?
If a tech worked on it take it back before doing anything to it, and explain what’s happening, they possibly didn’t reassemble it correctly or missed something.
It’s always a good idea to try and test it in store before taking it back incase something like this happens.
This 100%.
You paid someone to do a thing. They just need to try again. “Work warranty” is the term, and it means the tech messed up somehow.
Fubar on reassembly by the sound of it. It happens.
Not unusual to reassemble a blaster, find out there are issues, disassemble, find nothing amiss, reassemble the same way and it’s fine. 
As above though, tech work will be covered under a warranty so not getting too far into it yourself and returning it to the servicing tech’s your best option. 
ok so i found the problem, techy lost the ball bearing on the selector switch when he disassembled it (i know because i opened it and yep no ball bearing). spring was still there although i was thinking of buying a new set (ball and spring) cuz the old one before this was still a bit loose anyway. is that a good idea?
It’s only a small thing but shouldn’t have been given back to you with it missing… makes your select lever janky.
Sometimes it’s a ball, sometimes it’s a very specific nylon detent pin. I’d still make contact with the tech about it, but now that you’ve had that lever off they may assume that you’re the one who lost it.
The joys of DIY blaster repairs.
I had to replace the ball bearing in mine. I believe it was a 2mm bearing. I bought this kit off of Amazon: Server Busy
Which I use for replacing ball bearings when they go missing or are called upon for a 3d print project. There is no 7.5mm ball so I cannot be accused of constructive possession!