I really like your spirit "Can Do!" and the way you solve all problems that arise. Great to follow your development.
Sorry about the problems with the tamper. I am sure you will solve also those problems.
But just wanted to point out an alternative to consider.
We had an old, classic Matisa BL09M tamper bought for scrap price from Swedish State Railways some 40 years ago.
But in spite changing a lot of the parts, it continued to be quite temperamental.
Thus we bought a new one some years ago from this company in France, specialized narrow gauge equipment.
http://yves.ocquident.free.fr/Their product is a rather direct copy of the Matisa BL09, built with Chinese components. They can custom build what ever you like, and it does not cost a fortune. Our new unit works quite well.
http://museijarnvagenimariefred.se/flera-lyft-for-banavdelningen/More pictures from our 600 mm railway on our blog:
http://museijarnvagenimariefred.se/category/oslj/Dag B