You get what you pay for when it comes to motors and generators....
Realy this isn't bad at all considering how little these things cost. The surface rust you see on the pole faces is just comestic, but I would If I were you paint the stator and rotor with Glyptal 1201, CRC Clear Urethane seal coat or some other high quality electrical finish. Look closely at the insualtion class of the machine if its a unit with type F use something that will match it like the Gyptal. Type B Insulation the CRC or low grade product is fine
I can't be sure but If I recall the insulation classes are as follow
B- 120 c
F- 155 c
H- 170c
There are others but you don't see them much Like "C" "A" and "O". C is higher than H, A and O are lower than B.
Before you paint your winding clean them with a high quality electrical cleaner made for motor windings not "varsol" or "brake clean". Use light coats on the rotor, soak the hell out of the stator. Do this when the parts are cold so paint has some time to penetrate.
Is it the camera or did they use wood to wedge the rotor windings between the pole face and he rotor body. No big deal if it is we used wooden wedges in the motor shops for years....
Don't waste your time with fancy bearings or trying to find ways to grease and purge. Buy 2RS sealed bearings and toss them in the trash when they get noisy. 2Z bearings if you must grease them or it will keep you up at night, but this is a waste of time. 2RS bearings will last you years, no issues for an ST-5 I think you need 6209 2RS for the front and 6207 2RS for the rear. These bearings are HUGE replace them once with a good brand like FAG or SKF and you likely won't need to worry for years.
How to replace bearings pull off th old ones with a puller.....
Ask wife to leave the house, enjoy a day off and buy herself something nice.
Preheat her oven to 250 F
Warm bearings for 10 minuts a pound (joke until hot a little dab of spit will tell you your warm enough)
Slide warm bearings on cold shaft they should slip on like breaze. As extra insurance place rotor in freazer and put a tiny bit of oil in the shaft before sliding bearings
Last and most important: 1. Slide those bearings in all the way don't stop half way and let them cool
2. Never tell your wife you cook bearings in her oven and froze a rotor in the Freezer
Doug
Doug