Flashing on carbon brush, even after replasing field coil, armature and carbon brush.

If there is a dis balance in the armature a bearing was become hot and is not anymore in the center(middle) between the 2 stator coils the field magnet then one of the 2 carbon brush should become shorter then the other.
If there was too long a too much particulate matter in the vacuum cleaner bag then the motor was before running too hot with a lost airflow the field or armature become too hot and a thermal failure on one collector can made the difference , the color of the magnet field coils must be smooth and have not a dark brown color but have a fresh brass color the commutator on the armature have no great differences in the gaps between each other and if running the motor the rpm can sounds good but inspection on the sparks from the brushes is the first relation to see the color of the coils of the armature and the fieldmagnet but also the bearings must feel that its turns smoot. control the carbon brushes can be very important. not too short , if they too short DO NOT REPLACE BRUSHES if bearings color or the commutator surface is not smooth , change IF ITS rewarding only a motor like its a Kirby thats a choice here is how the color of the field should be

broken powercable , carbon brush (autostop or to short brushes) or the switch itself or one of the 4 coil (2 for one coil) contacts on the electric field can be broken or a collector on the armature is ruined .
first control only turn by hand the blade a littlebit to check the last option before you connect the wallconnector so it can start because if brushes stands on a defect collector it wont start , if it willm start and sparks replace the armature and maybe also the electricfield and also the drivinggear on the armature in some cases. if only to short brushes replace brushes.

Measure the value difference in Ohm between the carbon brushes on the armature there are some collectors in the commutator give an other ohm value if compared to other collectors in the comutator of the armature . if measure turn the blad very slow so the collectros can be positioned to measure the ohm difference. range to measure 0-200ohm on ohmmeter.
If only one brush made trouble ( much more sparking ) then the electric field is not in ohm value balance, control always if there are slide contacts used they are solid. on the field. Measure the difference. between the 2 field coils of the electric field . if its also different replace allways the field and the armature if thats also have problems (BUT DON,T FORGET to order a new drive gear for the armature and new brushes. !!!

Are you shure its the trigger careful with this conclusion it can be more simpel to measure or to find the defect part . look first if there is no autostop activated in one of the carbon brushes ! its a small pin that will stand out between the contact side and the commutator collectorsline of the armature if a carbon brush has short-length to protect the armature against the pressurespring of the carbonbrush .
second it can happend that one of the 4 electric field contacts are broken, and if one of the 2 coils are defect by measure to see replace always the powercable because of hidden defect
hitch and start clapping in the stator (electric field) are very high and thats the cause in most cases also be a much changed quick lock cable can cause. then a new connector block and cable replacement bijde, please note all cable and wires should not falter from the socket to the electrical field.

a bad centrifugal starter or inside capacitor and or the electric field if an old type with induction motor , but if it has carbon brushes in the motor instead of an induction motor the commutator on the armature short brushes or a bad bearing(s) on the motor or other gearbearings on the saw drive are worn , it must have a smooth turn if turn on the armature if remove the field /motor house.. look in the motor if running at the end if the carbon brushes you see are make to much sparks a worn bearing without the balls or bad armature collectors or electric field . watch if the bearing is worn by blue hot it can have melting the seat in the motor house replace it all.

It sounds like the armature is bad. It should have an even dark ring around the bars of the armature commutator where the brushes ride. If one or two of the bars is discolored above and/or below that it could easily be bad. It could also be pitted between a couple of bars. Normally the space between the bars is even all the way around and nice and "clean cut" looking. If you have access to an armature growler you can test the armature. Hope that helps.

it probably needs new carbon brushes in the motor,DO NOT run anymore for fear of burning motor out.

The field coil is the winding that surrounds the armature.. There's your smoke

the armature is shorting across the commutator bars and a new saw will be cheaper than a new armature

Yes, the bars on armature comutator are lifting, usually caused by heat. Only thing to do is replace armature and brushes, but best to also have field coil tested for shorts before buying new armature.