Excel VBA UserForm-Importing-Error: Item' could not be loaded

I have a lot of UserForms as *.frm/*frx in a folder. I do not have the forms in a *.xlsm-Workbook, as I only load the necessary Userforms by need into my workbooks.Importing the files worked for many years.Now I can't load a single of my Userforms into any Workbook anymore.

When importing any form by hand it throws this error:

https://learn.microsoft.com/en-us/office/vba/language/reference/user-interface-help/item-could-not-be-loaded?source=recommendations

Picture of Error-Message:Error Message

When I import the form by VBA with:

WBook.VBProject.VBComponents.Import Filepath.frm

it throws the following runtime-error:

runtime-error 50057

In some tries I also got a log-File, with following content:

"Row 2: Property OleObjectBlob in CODING__Form_VBEHandling could not be set"

I created a new UserForm in Excel and exported it. This Form can be imported without a problem, but all my old userforms throw the above mentioned error message.

So this seems as all my old Userfroms are broken.

If so, may there is a repair tool/ method for broken UserForms?

Thank you for any help to rescue the Forms!