Well end grain wood sealer is just emulsified wax , and since I don't think Epoxy will stick to wax, I'd have to say no. Preparation - I'd suggest going over the end grain sealer and see if it has any info on cleaning up dried / cured sealer However, as it likely will have penetrated wood fibers, just a surface cleaning likely would not do the trick either. In all honestly I never tried cleaning off end grain sealer (other than scraping thick deposit off to make pen/pencil marks before turning or cutting away the wood well past any sealer penetration) If it was me, I might consider trying hot met glue to hold things together enough to turn away the sealer (and then DNA to remove glue, heat gun to melt away wax, perhaps do the melting away first then glue & turn, then remove glue) but if you can cut away wood that might have sealer in the fibers, you might have enough wood for epoxy to adhere to? Just my thoughts... I'd defer to others more experienced with this, however.