The vendor seeking specific performance shall show an ability to comply substantially with his contract in every part and as to all the property. However, a vendor's want of title or other inability as to part of the property shall not be a good answer to the vendee seeking performance who is willing to accept title to part of the property, receiving compensation for the other part. If the defects in the vendor's title are trifling or comparatively small, equity shall decree at his instance, granting compensation for such defects.