Sounds like rubbing underneath platter - Numark TT1510 Turntable

The plastic base may have become warped or the metal platter was not reinstalled correctly after belt replacement.

Most platters are fixed by a horseshoe clip under the centre spindle. You might have to force-ably remove what is around the centre area to get access to the clip. You can glue it back on if the platter itself is fine and not warped. If it is warped it would be cheaper to get a new deck than search for a new platter.

remove the platter and watch closely if a part sticks out, it has to

Take off the felt and the platter. Take some lint free cloth and rubbing alcohol and rub down the pulley. You can also use compressed air to dry it off. Also use the same method to clean and dry the underside of the platter. Put the belt around the ridge on the underside of the platter. Put the platter back on the turntable. Reach inside the access window on the platter and grab the belt. Hook the belt around the pulley. Rotate the platter to make sure it won't fall off. Put the felt back on and you are ready to go!

1) Remove the platter - just lift up
2) Underneath the platter, you'll see a small lip section
3) Wrap the belt around this lip
4) Put platter back on turntable
5) Rotate platter until you see the motor shaft through the holes on the platter - a brass round looking piece
6) Pinch the belt around the motor shaft.
7) That's it.

- OPTiC
MasterTech
Digital Analog Therapy
Turntable Parts : Turntable Repairs

1) Remove the platter - just lift up
2) Underneath the platter, you'll see a small lip section
3) Wrap the belt around this lip
4) Put platter back on turntable
5) Rotate platter until you see the motor shaft through the holes on the platter - a brass round looking piece
6) Pinch the belt around the motor shaft.
7) That's it.

- OPTiC
MasterTech
Digital Analog Therapy
Turntable Parts : Turntable Repairs

1) Remove the platter - just lift up
2) Underneath the platter, you'll see a small lip section
3) Wrap the belt around this lip
4) Put platter back on turntable
5) Rotate platter until you see the motor shaft through the holes on the platter - a brass round looking piece
6) Pinch the belt around the motor shaft.
7) That's it.

- OPTiC
MasterTech
Digital Analog Therapy
Turntable Parts : Turntable Repairs

Lift off the rubber platter cover (the disk that records set on while playing) there should be 2 openings in the aluminum plate. Slowly rotate platter until you can see the pulley of motor. Lift aluminum platter straight up and off. Place belt around underneath pulley on platter. Reinstall platter to turntable. Reach through one of slots in plater and grasp the belt gently, line up slot with motor pulley and place belt over pulley (ensuring not to twist belt) rotate platter to observe belt, confirming correct installation. Reinstall rubber platter cover. VOLA!

Hi mcmassous
Refitting the belt is easy.
1.) Remove rubber pad/mat.
2.) Remove platter just beneath mat. Some platters are "press fit" onto the center shaft and seemingly can't be removed, the trick is to lift up on the platter while simultaneously lightly tapping on the top of the shaft with the handle of a screwdriver. While others may have a "E" clip at the base of the center shaft which must be removed with the a screwdriver, with care that it doesn't fly away before the platter can be removed.
3.) Use rubbing Alcohol soaked cloth to clean outside of large 'lip' or ledge underneath platter and the (usually) brass pulley shaft on platter drive motor which should now be visible.
4.) Install belt around the ledge underneath platter. Belt should be somewhat snug without falling off.
If the belt just falls of the rim of the platter, then it is failing and needs to ne replaced.
5.) Optional: Clean then Lube main center platter shaft of turntable with 3-in-1 oil or similar.
6.) Re-install platter.
7.) look thru 'access window' in platter and rotate platter until platter motor becomes visible.
8.) Stretch belt from platter ledge over to far side of motor pulley.
9.) Re-install mat and start player.

I am more than happy to answer any other questions you may have about it, just give me a hoy :) If you are still unsure, or have problems, then before you give a rating for this advice, please get back to me and we can try some more things.
Thanks for using FixYa, If you consider the advice I have given you as sound, a FixYa rating is a great reward for my efforts to help you. Cheers.

regards
robotek

I would suggest you verify you motor is sound, the platter is not rubbing. Is it direct drive or belt drive? You could go as far as check that your ac to your house is stable and the ac to dc rectifier/transformer/whatever it is called is good. When you say tables are new...as never used or made within the last 6 months?

More details on the tables would help.