I once was called out on a similar emergency case to this. A few of the hairy Amazonian elephants (with whom I am well aquainted) were worried that their pet humans were becoming unruly. This herd of females would behave exceptionally when encountering a male of their species. Although I could not completely solve the problem I did learn much about human culture.
I can therefore suggest several options; Sometimes the cries of pain are in fact perfectly innocent. Before proceeding you should discover whether Julia is actually in distress. Following a drastic corse of action before doing so may enrage both her and your original pet. The second thing that I suggest is that you aquire some form of lubricant. Such things are easily available in pet shops and industrial works. WD40, 3 in 1 oil and several other are all acceptable to even the most discerning of human pets. If this does not work you must be firm and confiscate any items your pet takes with him 'upstairs'. Ballons, kick-along stools and stepladders are among the worst items he could have. If there are still eerie noises, screams of pain and distressing cries that chill you to the bone then you are left with two options only, despose of Julia or... Buy a Wicked Marketing inc. Chocolate Chastity belt. This will ensure Julias comfort and safety at all times.
I hope that this advise will be helpful in your quest to keep your pets happy and that our other readers will draw some wisdom from this episode.
PS. If you do wish to dispose of Julia, could I have her?