This is an old post, where was this dug this out from? hehe 
Well, now im here….
To improve success on this probably impossible task use a high end audiophile belt drive turntable.
The rubber band helps iron out some of the tiny yet constant speed fluctuations from the motor.
Also both original and instrumental would need to have their own side of the record and play at the same speed (33/45)
If both are on the same side of the vinyl the 2nd track closest to the label will have lost a lot of dynamics, mainly in the
high frequencies as the needle is passing over the record slower than it was at the start of the record.
Try looking for the original on CD from ebay 
AdSense 336x280
