tonearm issue

You might want to simply level the whole suspension, Those springs are pretty loose and doing shipping will bounce around substantially. 

I have my suspicions, but frankly, I'd start from scratch.

1. Carefully investigate the tonearm wiring. Ensure there's no binding or pulling in any way shape or form. In fact, you might disconnect/remove the cartridge to help with this process. Only when you are 100% sure the wiring is up to snuff, remount/reconnect the cartridge.

2. Relevel everything. If the feet are adjustable, start by turning them all the way into the plinth. Check the level. Then slowly, slowly unscrew the feet, raising the plinth until it is dead level. Check and recheck. (OH! I hope you started on a level table or surface, yes?) 

3, Relevel the suspension. Put the bubble close to the spindle as possible. Even better get one of those records weights with a bubble level built in. 

4. I'm making a huge assumption here that you've correctly mounted the tonearm but check THAT mount to make sure it is level as well.

Once all that is done I think you can safely eliminate the TT as the problem. 

NOW you can focus on the tonearm. You say they worked on the arm lift mechanism? Make sure nothing else was knocked off kilter, the weights? Perhaps a bearing? Make sure you have a bright light to assist. Gently, carefully make sure the arm can freely move in all directions.

Now, zero out the antiskate. Gently set the needle on a non-spinning LP. (Use something you don't mind scratching, just in case.) That needle should not move. Period. Start the turntable and see what happens. The needle should track. 

What a lot of people don't realize is that "skating" happens as the mass of the cart and tonearm gain momentum as the arm moves towards the center of the record. Anti-skate is supposed to provide JUST enough pressure outwards to keep that from happening. My suspicion here is that somehow either the anti-skate mechanism has been compromised or a bearing is out of whack.

Good luck and let us know how it goes.

Happy listening.

Lots of great advice here, both on TT set-up  and on Cart parameters.

One small contribution - I suggest getting two or three CLEAN, OLD LPs to use until you have satisfactorily installed the TT and Cart.

They will be fine for your purposes and save you from possible a possible 'damit' moment...

Good luck

Even if you don't think using the blank side of an LP is the best way to SET anti-skate, it can be helpful, in your case, to reveal natural inward skating and IF your anti-skate control is capable to counter that with a smooth amount of too little, seems like enough, too much.

https://www.amazon.com/Turntable-Protractor-Anti-sliding-Calibration-Adjustment/dp/B08227CZPG/ref=sr_1_1_sspa?sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

Then, to refine my anti-skate by ear, I use combos of CD and LP versions of well known content.

IOW, to have confidence that the arm's controls are working properly 

Could be as simple not cuing the arm properly.