Henry Motor Seal Needed

Hi, I am a collector of Numatic Vacuum cleaners and I enjoy repairing them. All parts are replaceable apart from the motor seal it would seem without having to buy a whole new motor kit which are too costly.

I want to restore a green Henry HVR200 from 1997 fairly rare models but the original motor was too rusted/corroded beyond repair and I have a spare Numatic motor to put into it however the bottom rubber motor seal is not compatible which any other motors but the motor housing itself isn't much different to any other older Henry HVR200 but because the bottom rubber seal was different I now have a dilemma where I can not fit any motor into this.

I will try and attach a photo of the part I am talking about