My pump has not been fully priming and I've identified the cause... the union (I think that's what it's called at least) going into my pump has cracked:

For now, I've unscrewed and greased the connection, then wrapped the whole mess in plastic wrap and duct tape and the pump is now priming reasonably well. My question is... how do I go about replacing this? My assumption is that if I remove the top cap I could slide the entire pump backwards enough to remove and replace the cracked union:

(By the way- this is an old picture before the thing cracked when it was priming fine)
Am I off base here? Anything else I should be thinking about?
Thanks!

For now, I've unscrewed and greased the connection, then wrapped the whole mess in plastic wrap and duct tape and the pump is now priming reasonably well. My question is... how do I go about replacing this? My assumption is that if I remove the top cap I could slide the entire pump backwards enough to remove and replace the cracked union:

(By the way- this is an old picture before the thing cracked when it was priming fine)
Am I off base here? Anything else I should be thinking about?
Thanks!