Leon
I am surprised you have not received any thoughts on this.
Firstly, welcome to the forum and we hope to see the progress on your son’s future pagoda — pretty cool car for a youngster.
I don’t know what is the right way or wrong way - for my locks, which were a little gunky and a little sticky, I soaked the thing in a degreaser and used a brush to get as much off as I could. After a few minutes, I blew it dry and then used brake cleaner to get the rest of it clean. After I used a light oil. Inside the locks (key ways, I used a graphite.
Not sure if what I did is the right way, but there it is.
Good luck.