I would link the href for the thumbnail images in up-sells and related products to link to the full prooduct (the_permalink) not to the larger product image.
The page source was showing:
<img src="...the thumbnail..." alt="" width="276" height="213" class="colabs-image" />
<h3>product title</h3>
I have now modified content-product.php so that the result looks like this:
<img src="...the thumbnail..." alt="" width="276" height="213" class="colabs-image" />
<h3>product title</h3>
but can't get rid of the href on the image. In the product gallery, I have set the link url to "none" but this hasn't got rid of the href on the image. Template is Eureka.