Thats pretty much right! When using Powertools the AA site came up with a higher price, presumably based off their own fare rules, whilst the only OTA to come up with a price was Cheapoair and that failed at payment stage. Propellor travel turned it around same day.

Initially finding the fare in Matrix itself was straightforward starting with LHR HEL JFK LAX in the route coding. IB I class seemed far more readily available on the Finnair codeshare so i worked backwards from that.