I'm getting ready to replace an A9 cartridge bearing headset (new version) with the older version needle bearing type. I have no experience installing headsets. The one I'm replacing is the original headset installed on the frame by a competent bike shop. Does anyone know if the two headsets are similar enough as far as the prep necessary to install them, that the replacement would be a straight forward process of carefully changing out parts, or will special tools be required, in which case I will definitely take it to a good shop. Thanks in advance for any responses.