As someone with "no skin in the game" just putting a little logic to things this is what I would do. (Since I am over 1200 miles away there just isn't enough at this sale for me to consider the trip).
FOR THE AUCTIONEER:
Number machines BEFORE loading loading highest number item first. (Get that list published YESTERDAY) As you unload machines they would then hit the building in the "correct order". Just start lining them up "#1 first and so on" and all is well.
Post list of machines & order of sale ASAP. Post it here as well as having paper copies at the sale.
Sell machines one at a time NOT CHOICE from a group - buyers don't like buying that way and it just makes things harder to follow. (Announce how you will be selling ahead of time so bidders know how to prepare or if they even want to attend)
FOR THE SELLER:
Don't hold back the "better stuff" - that stuff is what will get people to the auction.
Finalize things with auctioneer YESTERDAY - don't keep people guessing this is going to cost you money in the end. People are not going to drive several hours to attend a sale if they don't know what is actually getting sold (COMMON SENSE!).
TO LOCAL BUYERS:
Don't miss this sale just because of last sale this auctioneer did. The way seller is handling things here (not blaming the auctioneer at this point) this has "buyers sale" written all over it.
My background: 30+ years in the antique business before getting into pinball machines. Have worked for several auctioneers & attended hundreds (if not thousands) of auctions. NOTHING to gain by making my thoughts public on this sale!