High revs saw is reving very high rpms and tripping 15 amp breaker

check that the 110 is the same as the mains supply to the house
if it is , take it back for a warranty replacement as a 15 amp breaker should be 5 amps more than needed
possible earth leakage ( bad insulation) faulty manufacturer --short
the tripping breaker is an indication of a serious fault in the machine either voltage or manufacture

What is the rating of the breaker? Is this enough to run the saw? If this is ok, has the motor become damaged or has the blade got dirt or wood dust slowing it down?

If the saw is tripping breakers, either you are trying to run the saw on a circuit that can't handle the amps the saw needs to run or something is wrong with the saw that is making it draw more amps than it should.
Power supply: You should be on a 15 amp circuit or higher for this saw. Popping breakers can also be caused by using long or low guage extension cords or a low guage power cord on the saw. The saw should have a 14 guage power cord on it and extension cords should not be lower than 12 guage if 50 feet long.
Saw: You've already replaced the cord & switch, if the brushes are OK, look to the mechanics of the saw. The blade should turn freely and smoothly by hand with the saw unplugged. Things to look for are a lack of lubrication in the transmission, binding or broken gears in the trans and binding or seized bearings on the armature or worm gear set. Also, a dull blade forced through wood will also cause the saw to be overworked and draw enough power to trip breakers.

Usually a saw that size will have it's own breaker built in, is this the one that is tripping? Or is it the one on the wall? Either way, a dull blade will make the saw work harder, and heat up faster, Mine trips off now and then, always from a dull blade. It has a built in breaker in the switch. Are you running it with a cord? Make sure it is heavy enough, a small cord will steal amperage from the circuit turning a 20 amp breaker into a 15. Hope this helps.

Making sure the saw is unplugged ( not just turned off ) and using a pair of heavy gloves, grasp the saw blade carefully and see if it turns freely. If not then dis-connect the drive belt from the saw and try again. If he saw turns easily now and make no grinding noises then it appears your trouble is elsewhere. While the belt is dis-connected try to turn the motor my hand. It should turn smoothly but with a little resistance. If it turns ok then we must look elsewhere again.

Look at the specifications plate on the saw to determine how many amps the saw requires to run and then check the rating of the circuit breaker that trips when you turn on the saw. If the saw requires 15 amps to run and is on a 15 amp circuit then it needs to be relocated to another outlet, preferably one with a 20 or 25 amp breaker.

Look at rating plate on motor.
Look for volts, watts, amps.
Figure with Volts x Amps = Watts.
Amps = Watts divided by Volts
1 hp horsepower is 756 Watts.

Lets say you have 120Volt 2hp motor
So 2 horsepower motor draws 1500 Watts
Amps = 1500 Watts divided by 120Volts = 12.5 amps = so you need 120Volt 15 amp breaker with at least 14gauge wire (as long as motor is located within 50 feet of breaker.)
If motor is farther away, then you need 20 amp breaker with 12gauge wire.

Look at circuit breaker rating.
If motor is 240 and breaker is 120, then it will trip breaker.
If motor is 120 and breaker is 240, then it will trip breaker.
If breaker is for 15 amps and motor draws 20 amps then it will trip breaker.

Generally speaking, if motor and breaker are 120V, then black wire goes to black wire; white wire goes to white wire and green wire connects to bare copper wire.
If motor and breaker are 240V, then wire colors can be different. Black-red or Black-white from breaker connect to Black-red or Black-white at motor.

Add a comment. Say the motor rating and color of motor wires. Say the breaker size and color of wires coming from breaker and I will help you wire the device.

These saws have a rather large amount of draw on a 15 amp breaker... they should be able to operate on a 15 amp breaker, however nothing else can share that breaker.... and if it is an outside plug (GFI) it will be even more likely to trip. If possible, use a 20 amp breaker...they can be found in the garage where central vacuum plugs in. If this isn't an option then ensure nothing else is on a normal 15 amp breaker, use a heavy gauge extension cord, and the shorter the cord the better.

start off with the low speed screw turn it right in then undo it 1+1/2 a turn start saw up and screw slow running screw in or out a little bit at a time till the saw ticks over,,then give the saw full throtel and screw the fast screw in or out till the saw is reving as fast as it will rev at

I don't care what kind of stories Craftsman tells, their numbers don't add up.
One horsepower is ~ = 740 watts of energy.
2.5 hp equates to a steady-state power consumption of  ~1850W and this could be 50% higher during the first second or two after turn-on.  Your 15 Amp circuit is pushed to the limit by that power level; 15 Amps X 120 VAC = 1800W And, motors aren't a breakeven game; part of the power they draw is wasted in heat.

9 amps steady-state would be a power consumption of over 6kw which cannot be right. Either your measurements or the motor is faulty. 

More than likely motor but try this , if you have a wrap around amp probe or can borrow one or purchase a cheap one place the amp probe around the positive wire connected to panel breaker ,with meter on proper scale ,start saw and read probe current , if cap bad current will be high and stay until breaker trips , if motor will start high on start ,then low then ,very high and breaker will trip , be careful in panel working around live circuits , the reason it reads this way is because as the motor warms the laminates it the armature separate and cause the increase in current to spike ,if cap bad never gets to speed and has high current draw constantly , to verify cap(1) remove from circuit (2)place a screw driver across terminals to release any charge (3), then take ohm meter on ohms place meter leads on terminals one on each terminal at same time meter will rise and fall back(4) reverse leads and should rise and fall as before if it does this it is more than likely good a lot of electrical reasons for this but this will tell you what you wanted to know , good luck