I don't like sucking either.
For clarinets, I block the end of a section, block the back of my throat, and "squirt" a mouthful of air gently into the instrument. Loss of pressure inside the mouth indicates leakage.
If I then blow hard (from my lungs) the offending pad will often be the first to lift, as air nosily escapes.
However, I, like most technicians, eliminate leaks as every pad is installed, using a thin membrane "feeler", testing for differences in closing pressure around the pad. When the repad is finished the "squirt" test should show little or no leakage, especially on a plastic clarinet.
There are MANY approaches to installing clarinet pads. Mine is as follows:
I use glue-gun type glue in amber pellets, from J L Smith. I put one or more pellets - quantity is critical - into the key cup, and heat the key cup over a Bunsen burner (off the instrument) until the first visual sign of softening of the glue. This means that this particular type of glue is soft enough to move and to stick. (You need the right glue to rely on this sign!)
Then I gently place the pad in. Then squirt a spray of water (from a spray bottle) onto the (doubled-up) smock covering my thigh, and wipe the back of the key cup over this until there is no longer any audible sizzle - a couple of seconds. This means the glue is at the right temperature for "massaging" the pad firmly, into the pad cup, ensuring it is evenly level all the way round. (BTW pads must not project too far beyond the cup, or you will have stuffy sounding notes from poor venting!)
Install the key on the instrument, and use appropriate tools to adjust the alignment of the key cup over the tone hole such that the pad, as tested by the feeler, is closing evenly all the way around the tone hole. (No reheating and adjsuting the pad crooked in the key cup!) Then press the key cup firmly with my thumb, and give final check. Done. Sometimes I "iron" a pad with a pad slick to flatten the surface more, and improve the "immediacy" of the closing.
It is worth noting that a repadding job is very seldom just a repadding job, because a repadding job is useless unless tone holes are level and blemish-free, posts are securely mounted, springs (especially throat A) operate freely, pivots are not sloppy, pivots are free of excessive friction, springs have appropriate tension (and the amateur is likely to muck it up for a few of them!), silencing materials are doing their job properly AND reliably, linkages are accurate and reliable, linkages are free of friction, etc, etc, etc. This is where the expertise of a good technician is invaluable.
Aust$260 is cheap. Either the instrument is in excellent condition, or the technician is likely to skimp on the job, either by choice or by ignorance.