Patek Philippe GENEVE CALIBER CH 28-520 HU Manuel D'instructions page 18

If you notice that your watch exhibits such
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irregularities, please do not hesitate to take it
to an Authorized Patek Philippe Retailer or an
Authorized Service Center where no effort will
be spared to assure that it is adjusted to meet your
expectations.
water resistance
Your watch is fitted with different types of seals
to protect the movement against the ingress of
dust and moisture and to prevent damage if it is
immersed in water. Nonetheless, we recommend
that you prevent direct contact with water if your
watch has a leather strap.
service
We recommend that you have your watch serviced
at least once every five years. For this purpose, we
suggest that you bring or send your watch to an
Authorized Patek Philippe Retailer or an Authorized
Service Center. This gives you the assurance that
your watch will be entrusted to hands of a qualified
Patek Philippe watchmaker in Geneva or at one of
our Authorized Service Centers around the world.
The watchmaker will completely disassemble the
movement and then clean and inspect all parts
and lubricate them in the reassembly process. All
functions of the watch will also be tested in detail
and the escapement regulated if necessary. Finally,
its rate accuracy will be monitored and precision-
adjusted for a further period of two weeks. The
entire process may take several weeks because
each watch must undergo a complete series of tests
to fulfill the strict quality criteria of Patek Philippe.