You accidentally unscrewed part of the zoom eyepiece assembly while removing it from the scope by twisting the eyepiece instead of the knurled ring on the Regal.
Here are the Regal and zoom eyepiece normally assembled.
Here is the pair normally separated.
The eyepiece should be removed by twisting the silver knurled ring on the scope, not by turning the eyepiece. If the disassembled pair looks like this
with threads on both the eyepiece and a threaded piece still inside the scope, then you have not properly removed the eyepiece.
To get the chrome eyepiece barrel out of the scope, loosen the knurled ring on the scope by turning it counterclockwise (opposite the lock arrow direction engraved on the knurled ring). Tilt the scope over a surface to catch the barrel.
You may need to gently shake the scope to have the barrel fall out.
Reassemble the eyepiece by simply screwing the barrel to the lower part of the zoom eyepiece housing.
To prevent this from reoccurring: 1) use the knurled ring to mount and remove eyepieces, 2) try not to over tighten the knurled ring and 3) try not to overturn the eyepiece when zooming it.