Hi from a new guy. No sales nor self-promotion intended here, but if you're using film cameras you may also be faced with light leaks as those cameras are aging. Additionally you may be hampered by a lack of camera repairmen still in business today, so stopping those leaks may be something you need to learn to do on your own. Light leaks ruin film which isn't nearly as easy to get today and waste the dollars you've spent on developing. If any of this seems to apply to you, please feel free to read several instructions I've written on the KYPhoto site.
Hope it helps. If you have any questions at all, please contact me.