I have run into that
Without getting technical about the construction
of the adjusting mechanism
Lower priced or older scopes ( lubricant dried out )
That is just one of the differences between lower
price and quality scopes
I no longer even look at cheap scopes
You get what you pay for
I am ashamed to admit how much money I wasted on
cheap scopes trying to save some money
I still can not afford the top of the line scopes
but am happy with medium priced scopes, the brand I
have found is Leupold ( Lifetime Warranty )
I no longer need a screw driver to tap on it or send a
couple of rounds to get the scope settled in to where I
adjusted it
I have even forgotten some of the four letter magic words
I used on all the cheap scopes I waisted time on trying to
adjust