checking platter speed

Two questions:

1) How can I be sure that my platter is rotating at the correct speed?

2) If my platter is not rotating at the correct speed, how do I remedy this?

I have a Clearaudio Emotion turntable.

Thanks in advance for your help.

I'll second the KAB Speed Strobe. I use on on my Galibier and really like it. Remember, anytime you check the speed be sure to have the stylus tracking in as dynamic a passage of music you have.

As far as what you may be able to do if your table is a bit off, that's a bit tougher. You may be able to play with the belt tension, and maybe even material, to improve things if the speed is not off too much.
I am sure it is very unscientific, but if you have a CD and LP of the same music, put them on simultaneously and see if they are together by the end of an LP side. That assumes of course the CD is'nt remastered or otherwise mucked around with.
Talk to your Clearaudio dealer about their strobe disc and speed sensor. It runs at 300Hz and is much more accurate than the usual 60Hz type.

dealer disclosure.

It runs at 300Hz and is much more accurate than the usual 60Hz type.

Will that be because you strobe at 300 Hz then divide that by 5 just like calculating the 72 degree from a 360 degree pulse?

The KAB speed strobe specifies 99.99% accuracy at display frozen. The exact figure quoted was 0.03% off from 33.3333333..nnn.... rpm. How accurate do we need to be if a speed change alters pitch barely at 6% according to KAB and if the usual/typical "broadcast accuracy" is at 0.3% off pitch?