All of these questions have been answered before, thoroughly, by Ashby. You can kill an elk with just about anything, but if you want to increase your odds, then shoot a durable arrow, that is perfectly tuned, front-heavy, with a narrow single bevel, that weighs 650+. Your bow is perfectly fine (unless you need an excuse to buy a new one!)
Now, your current arrows can be tweaked to fly well with more point weight, by experimenting with different length footing. Adjust the footing length to allow you to add more weight up front -- longer footing will make the shaft act stiffer to make up for more front weight. This is far superior to internal weight tubes/line.
I can tell you that I have two regrettable occasions where I have shot elk with a longbow and arrows/broadheads that did not meet the above guidelines. I will not make that mistake again.
Pete