OK, makes sense. Thanks all for looking into this.

The internal energy buffer's an interesting quirk. I guess it makes sense, but I'd not noticed it documented before.

> If they eventually run fully out of power they are stuck forever until something *externally* puts fuel in them.

This doesn't quite match my experience. When I place a new burner inserter, it grabs an available fuel item for itself, without my having externally put fuel into it.

Save game file available at: https://drive.google.com/file/d/1Udwrbx ... sp=sharing

What did you do?
I have set up burner inserters to remove spoilage from bioreactors.
Initially the burner inserter fuels itself with spoilage and operates as expected.

Probably irrelevant: each inserter has a filter set to whitelist: spoilage (no quality overlay – i.e. quality 1)

What happened ...

Thanks for the tip. Good to know there is an alternative approach. To be able to copy and paste would still be useful for small ad-hoc edits that don't warrant the somewhat more involved (or at least intimidating – I've never quite mastered it) upgrade planner interface – though I appreciate you ...

An assembling machine cannot be upgraded to a higher level machine with a higher quality.
To reproduce:
1. Place an Assembling Machine 2.
2. In remote view, copy an existing Uncommon Assembling Machine 3
3. Attempt to paste the Uncommon AM3 in the place of ("on top of") the AM2
4. Note error ...