Difficulty with clone/heal

I'm a novice LR 11 user, finally reverted to subscription after sporadic use of LR 6.

I'm having trouble using clone or heal to remove large objects from a jpg file.

I often end up with orignal background bleeding through my image after using clone/heal or using a brush to create a mask.

Here are my brush settings and the results I achieved.

Using a PC with Windows 10

Appreciate any suggestions or pointers to tutorials....Strangely enough, <grin>, on the tutorials I've watched, the clone/heal or masking works perfectly