Platter wobble


I have a Technics SL-BD20D and the platter has a noticeable wobble while spinning. ive tried a couple mats - cork and acrylic - which made the wobble much more apparent.  The rigid acrylic platter would not lay flat on the platter. 

Anything I can do? Is there a way to test what the issue is?  Is there an quality aftermarket platter that I can use?

Thanks!
leemaze
The way I figure it since many LPs are not flat it will all average out. 
Or if MDF isn't good enough you could upgrade to IKEA bamboo
https://www.youtube.com/watch?v=1sp37DxnKDY
Note this whole turntable cost less than the Technics. 
Dear @leemaze: What are you waiting for ? , just from the very first post in your thread @noromance  gave you the rigth answer, now it's up to you.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.