Have you checked the belt tension also are you using sharp tools as blunt tools quite often leads to pushing harder to make a cut and then this causes undue pressure on the machine?
If I remember this is a smaller lathe and not designed for heavy cuts or over large/heavy pieces.
If spindle turning have you overtightened the tailstock again this puts extra pressure on the headstock.
thanks for your response, the gouge was just sharpened, and I'm pretty sure the belt is new, not sure how to improve the tension to be honest i had a look at the weekend and there's no adjustment as far as can tell - its an awvsl1000, 750W power ? i was turning a bowl about 6" in zebrano. it surely shouldn't grind to halt under the lightest of pressure ?
How long have you had the lathe?
Did it perform OK before or has it always been this way?
Does the speed adjustment work smoothly?
Have you lubricated the motor drive shaft ?(grease nipple in the end)
Check that the cone pulley half nearest the motor body has not moved nearer the motor body, grub screw loose. Belt should be at outer edge of motor pulley with high speed selected.
I know you say the capacitor has been replaced but this is the obvious suspect, are you sure the connections are sound, and was it a Run rated capacitor fitted.
(A start rated would work for a while but likely to fail if it overheated)
I used to own an AWVSL1000, take the cover off the motor and have a look at the belts when in use. Perhaps get someone to film it for you while you turn. Look at what the belts are doing, they might be slipping or there may be an error with the belts tracking properly. Try changing the speeds and looking what they do.
I had to replace some of the pulley as it the belt would slip and there would be no torque. Axminster sold me some parts and the lathe was good as new.