Changed KiHa 23 brought from Japan trip to HOm gauge from HO. Now looks much better and closer to prototype.
For this photo I have used KiHa 40 wheelsets, but eventually I have adjusted KiHa 23 wheels as well.
I have cut plastic tubes on KiHa 23 wheelsets and adjusted axles, so KiHa 23 now has its original wheelsets changed to HOm gauge and KiHa 40 has its wheelsets back.
Researched micro coil solenoids and old mobile phone vibration motors use for automating couplers and doors. 0.04 mm enamelled wire is available on eBay in 100 g 9 km rolls. Coil resistance should be between 50 and 200 ohms. Magnetic power is proportional to turns count and current value.