TEAC has a parts department and also some parts resellers. In the UK you go through Charles Hyde.
Last I saw 38/TSR heads were about £300 each. The erase heads aren't available anymore, though.
What's wrong with it, anyway? I had a head on a '32 once that I thought had failed in one channel, but was actually deeply covered in crud. You can also get the heads relapped if they have uneven wear.
In principle it should be possible to rebuild them too by sputtering more material on them, but no-one seems to do this.