Happy new year to all.

I am adjusting the top tube length on a couple of bikes by installing different stems. The bikes came with short stems. I have road style handlebars, and the older style stems that do not come apart. The reason these replacement stems are useful is that they are the right (longer) length and they fit into the steering tubes of the respective bikes. Also, of course, because they are here and now. I would rather keep these stems than to buy newer vintage. To get the bars into the stems, I need to somehow open up the jaw of the stem.

I tried wiggling the stem back and forth. But there is not enough opening in the jaws to do it smoothly, or even at all. I looked on Youtube for help. But the demos I found were all for the newer stems that break apart. Does anyone have any ideas?

Thanks in advance.

Saul