Not many of those around now (not that there ever were).
You may be able to get something from a USA supplier, but I'd start with stripping it and seeing what's what.
It's often possible to find seals of the correct size by taking careful measurements and then trawling through seal stockist websites - I saved a lot of money during my time with Sharp Innovas doing that.
Of course, if the manufacturer has had custom seals made then it gets more difficult.