Motor pulsates When I pull the starter and keep it above the floor it runs fine. When I put it on the floor the motor pulsates a few times then shuts off.

ok, you need to bypass the auto shut of. Put the vac on it's side and pull off the sliders on both sides.Carefully pull machine apart.lift the front of the piece that hold you bag.Underneathe there is a clear tube plugged in to a round thing on switch area.Simply pull the tube out of the rouind trhing.This will allow you to fillthe bag without shut dow.Just make sure your bag doesn't get too full....Chris

There are a few things it could be. Pull the handle back into the vacuuming position and turn the brush bar switch on and off while listening to see if you can hear the brush bar motor turn off and on. If you can hear the brush bar motor running it may need a new belt and/or the brush bar may be seized up.
There is a switch by the main power switch that provides power to run the brush bar motor. There is a micro switch down in the motor area that closes the circuit to the brush bar motor when you pull the handle back. Check electrical connections and all of the above parts to determine which one or one's may be defective.

There are a few things it could be. Pull the handle back into the vacuuming position and turn the brush bar switch on and off while listening to see if you can hear the brush bar motor turn off and on. If you can hear the brush bar motor running it may need a new belt and/or the brush bar may be seized up.
There is a switch by the main power switch that provides power to run the brush bar motor. There is a micro switch down in the motor area that closes the circuit to the brush bar motor when you pull the handle back. Check electrical connections and all of the above parts to determine which one or one's may be defective.

yes it can be fixed, the brushes on the motor are worn out. take it to a vacuum shop and they'll replace the brushes at a fraction of the cost of a new machine

Vacuum cleaners have electric motors in them that require proper airflow to pass over them to keep them cool. Many vacuum cleaners have a thermal (heat) sensitive shut off mechanism built in. This mechanism should prevent the burn out of the motor. If you run a vacuum too long with a clogged hose or clogged filters (especially bagless vacuums) or clogged bags, that is essentially choking the vacuum for air and not allowing it to breath properly. This will cause it to overheat and shut down. Most of the big box store purchased vacuums have very thin wires in the motor windings and can only do this a few times before the motor completely fails. If your vacuum has been shutting down, then cooling off and restarting after about 30 to 45 minutes, then shutting down after only a few minutes of use, your machine is probably clogged up or the filters are compacted.

the motor is heating up to much and the cut out switch is kicking in. You need to check the the motor filter, and worse case you may need to new motor..

It's possible the thermal reset is defective. It shuts the motor off if it gets hot. Remove the bag door and take the bag off, remove both filters and then turn the vacuum on, just leave it sit there with the motor running. This eliminates the bag or filters causing any airflow resistance. If it still shuts off after a few minutes it's likely the thermal reset is bad. Some vacuums have an external thermal reset button which can be replaced if necessary but on your model it is built into the motor and you must replace the motor. If the motor runs fine put the bag and the filter under the bag back in - (make sure the filter is clean and not restricting airflow) put the bag cover on then turn it on again. If it overheats and shuts off then you may have a clog on there somewhere restricting the airflow. If so check the power nozzle area, the hose coming from the power nozzle, the extension hose and wands for clogs or restrictions.

It sounds like you have a motor protection fuse that resets after an overheat/cooling cycle.These work the same as a circuit breaker in your house with the difference being they can reset themselves.The Bosch will also shut down if there is insufficient airflow and I would check your filters first.1) Pull the filter and let the machine run.Do not pick up debris when you operate without a filter-it will be drawn straight into the motor.If it runs fine without shutting down, all you need to do is change your filter.If it shuts down again check the external hose for any blockages.Also check the throat from the powerhead for any blockages.If you continue to have the same problem then you will need to replace the fuse because at this point you have eliminated all the other likely problems.Good Luck-Scott

The whine tells you taht the bearings are bad. Now they may be putting a drag on the armature and causing it to shut down after getting hot. You will have to replace the motor.

Sounds like you have a clog, either in the hose, or the inlet down at the bottom. When there is a clog, the red light will come on and may also shut down to protect the motor.