Once you are happy with the height of the rubber feet, you can solder the two 14-pin female headers in place. To assure alignment, it is best to leave them attached to the DRO-350 and solder them with the DPU-550 mounted in place. Solder all of the pins in positions J16 and J17. You should now be able to lift the DPU-550 off of the DRO-350 and the female headers will be attached to the DPU-550. Hopefully, you will never have to remove it again but using removable connectors is cheap insurance.