Very interestinginfo Mark.
I also use a lot of recycled timber and pallets are high on the list for use.
To get them apart I use brute force for example to get the first slat off I usually lever it off with a other piece of timber as with you I find the weak link to start.
Once this is off flip the pallet on the driveway, elevate the pallet by placing a block under the top slat and then thumping the bearer again displacing the slat and nails, repeat and I have a slat with the three rows of nails almost straight I then just bash the slat nail points down in the concrete to raise the heads then remove them. Mind you subtract about 10 years from the age group !!

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Regards Rob