Two comments:

1) it is most likely the foam seals around the film door have deteriorated. This is common and you can easily replace them yourself.

2) OM-10 had a problem with "sticky magnets". This is when a drop of oil gets on the magnet that controls the shutter and keeps it open too long. It could be causing your shutter to hang up. This can be repaired by a service shop or you can do it yourself - but it is not so easy as replacing the foam seals.