Thanks to all for the suggestions.
Here is the results of weeks of part-time work (part of that was waiting for parts.) Hope it helps others.
I have it running fairly well at around 13-14 V, which means maybe 70 % of the time it works.
In summary, the key items were reducing the load on the vibromotor and finding the right spring and string and wrap for the motor.
I sensed the load was too high since I added so much weight to the counterweight to keep the hoist in position during lifting. I don't have the original weight.
To reduce the load I reduced friction everywhere and made sure string wasn't twisted and was running in the pulleys correctly. Also cleaned the string going to the hoist with naphtha and added some graphite.
A key issue that was not obvious was the traveler was causing significant drag because the previous owner used oil on it. It was more like dried out gummy oil so I wasn't visible. I discovered this when I manually pulled on the string from the lower pulley and sensed this was too high a load. So I sprayed it with contact cleaner numerous times and used air in can to blast it clean. That made a big difference and then I was able to reduce the counterweight.
The replacement string I bought turn out to not be usable for the drive motor. It seemed to be too thick. Pulley would not move. So I got 2 different braided fishing line. The thicker one worked the best (maybe 20 - 30 lbs.) and it was much thinner that the Lionel PN replacement string. The wrap around the pulley that worked the best was 360 degree. I tried a 1/2 and 1 1/2 wrap but the 1 wrap was the best.
The hoist still wanders on it way down so sometimes it grabs the culvert off to the side which causes it to hit the ramp. The hoist also starts to traverse early on some pickups, but I can live with that occasional miss. Adding counterweight would solve this but load goes up.
Overall, just a lot of trial and error, with good observation to point to solutions, and help from the forum. Interesting project. I was close to converting to a DC motor.
Thanks again,
Bob
