How do I stop the Humming from my LP12?

I've gone through a process of upgrading my TT's over the last 2 years, and seemingly every time I make an adjustment or swapped equipment (ie Tables, Arms, Cart's, Pre's) had similar issues surface. Here's some of the problems I've encountered:

first the easy problems that can be solved with repositioning and or cleaning connections -
1) Poor interconnect cable connection between preamp and phono pre. Poor ground connection - on preamp, on table, or on the arm.
2) poor cartridge lead connection (between cart and arm)
3) Table in too close proximity to preamp. Be careful not to position your preamp close to and directly above or below your table.

Now the harder problems -
4) bad ground post on my preamp (yes, the assembly at the factory was incorrect).
5) Bad Cartridge - I had to send it back for warranty service on a ground connection.
6) 60hz feedback from motor to cartridge - some cart's are susceptible to this. My Grado Sonata just did not like being mounted on my Heybrook TT2. The closer the cart got to the center spindle (and the motor), the louder the hum got. This is a problem only with 120V motors. 12VDC motors shouldn't be a problem.
7) Bad wiring inside the tonearm (this is a problem with buying a used tonearm) - had to be re-wired.

I also found that some cartridges are much harder to get quieted down, while others are easy. And finally, as Pbb indicates, expect more noise than you're use to with cd player.

Where can I find the ground wire on the Linn Sondek Lp12?

It should be on the tonearm cable. If not add one the chassis or tonearm. There should be a screw someplace you can loosen and wrap a wire around.

You might want to check under table there is a ground wire that is grounded to the chassis it can come loose and cause a hum. Take your outer plater off and then support the inter platter or remove it. Make 2 stacks of books and place table on them so you can look under the table to find and follow the ground wire coming from tonearm area to the chassis. Mine has done this to me twice in the last 4 or 5 years it will produce a fairly loud hum. If you touch the cartridge mounting screws or touch tonearm does it get louder.

Oh, someone already pushed an old thread from 2007

It is interesting, because a few members bulled on me when i said something about Linn Basik quality.

Pretty funny, you guys must face it (about the belt drive):

I purchased a used Linn LP12 ... My second problem is that with the table set up according the instructions I can hear the belt rubbing against the top of the guide that it threads through when it is spinning. Even when I try to adjust the belt to the bottom of the subplatter disc, and then replace the platter, the rubbing continues.