I can't export the bookmarks from the broken iMac because its video has failed, but I can access the contents of its HD over the network and can see the ...Library/Caches/Firefox/Profiles folder. It seems empty but Get Info tells me it contains 380.5 Mb. I would like to somehow copy and paste the data onto a second Mac, over the network, then merge the two sets of bookmarks (but would settle with exporting the second Mac's bookmarks, then overwriting them with the iMac's, before re-importing the exported bookmarks to create a merged file). Everything on the iMac is backed up on Time Machine if this helps, but I don't use iCloud.