Last night I was making another pair of the HK-50 jigs from that same piece of oak that I used the day before to make a pair. I wanted to do it while I still had the table saw out as my shop does double duty as a garage and when both cars are in there the table saw is rolled off to the side, covered up, and used as a platform for my Tormek. (I found a way to keep this post on topic!) 
Link to table saw literature: http://www.mikestools.com/download/DeltaTableSawManuals/34-670.pdf
I made a cut, then when I went to switch it on to make another cut there was nothing. I checked that it was still plugged in to a powered source. So, I flipped it over and checked the switches. Both were good. I hooked it back up and it worked. So. I flipped it back upright. Then it didn't work, then it did. One time I had to give it a spin to get it started. I noticed a lot of sparks flying out of the motor towards the blade. So I took the blade off, blew compressed air into the motor housing, put a blade back in it and was able to finish up my work. This morning I made the final cross cuts that turn the single piece into two jigs and finished them up.
I flipped the table saw over again, but this time onto a pair of saw horses so I wouldn't have to work on the floor. I took the base off, and removed the motor. I took the fan pulley housing off and removed the brushes. I blew compressed air into the motor from both sides and also through the two holes where the brushes go. Put the brushes back in and bench tested the motor. No more sparks. Blew some more compressed air into it while it was running.
Link to motor literature: http://www.ereplacementparts.com/delta-34670-type-inch-table-saw-parts-c-3275_3334_7069.html
I wanted to replace the brushes so I went searching in vain for them at Lowe's, Home Depot, and Sears Hardware. I looked at photographs of the replacement brushes on the web and they don't look much longer than the ones I have.
Link to brushes: http://www.ereplacementparts.com/brush-sold-individually-p-57904.html
So, I used this opportunity to clean and lubricate all the linkages that adjust the blade height and miter angle, put it all back together and I think I'm good to go.
Could it be the sparking was due to an accumulation of dust inside the motor? Back in the day when I was a carpenter and doing trim work (2nd fix) the boss regularly cleaned his table saw motors by blowing compressed air into them while they were spinning. It's not safe to do that to this saw unless you've got the saw upside down, so I never did it. I did blow the dust out on occasion, but not while the motor's running. and not in recent memory.

Link to table saw literature: http://www.mikestools.com/download/DeltaTableSawManuals/34-670.pdf
I made a cut, then when I went to switch it on to make another cut there was nothing. I checked that it was still plugged in to a powered source. So, I flipped it over and checked the switches. Both were good. I hooked it back up and it worked. So. I flipped it back upright. Then it didn't work, then it did. One time I had to give it a spin to get it started. I noticed a lot of sparks flying out of the motor towards the blade. So I took the blade off, blew compressed air into the motor housing, put a blade back in it and was able to finish up my work. This morning I made the final cross cuts that turn the single piece into two jigs and finished them up.
I flipped the table saw over again, but this time onto a pair of saw horses so I wouldn't have to work on the floor. I took the base off, and removed the motor. I took the fan pulley housing off and removed the brushes. I blew compressed air into the motor from both sides and also through the two holes where the brushes go. Put the brushes back in and bench tested the motor. No more sparks. Blew some more compressed air into it while it was running.
Link to motor literature: http://www.ereplacementparts.com/delta-34670-type-inch-table-saw-parts-c-3275_3334_7069.html
I wanted to replace the brushes so I went searching in vain for them at Lowe's, Home Depot, and Sears Hardware. I looked at photographs of the replacement brushes on the web and they don't look much longer than the ones I have.
Link to brushes: http://www.ereplacementparts.com/brush-sold-individually-p-57904.html
So, I used this opportunity to clean and lubricate all the linkages that adjust the blade height and miter angle, put it all back together and I think I'm good to go.
Could it be the sparking was due to an accumulation of dust inside the motor? Back in the day when I was a carpenter and doing trim work (2nd fix) the boss regularly cleaned his table saw motors by blowing compressed air into them while they were spinning. It's not safe to do that to this saw unless you've got the saw upside down, so I never did it. I did blow the dust out on occasion, but not while the motor's running. and not in recent memory.
