Seattle has many homes close to 100 years old and a lot of them have the original locksets that were installed all those years ago. Of course over 100 years the intricate parts inside a lock might wear down or break and while many of these locks are still working just fine there are probably just as many if not more that are limping along with quirks that require special knowledge of how to use them.
While I think it is preferable to fix mortise locks, I understand if people want to modernize. There are options available to them. Instead of fixing the mortise lock it can be replaced with another mortise lock. For budget conscious people such as landlords not willing to lavish their tenants with expensive locks, another choice is retrofitting the door with conventional tubular locks such as those available at big box stores. They are inexpensive and easy for the owner to replace themselves, and everybody knows how to use them.
To retrofit the door for these locks a great deal of work must be done. New holes must be drilled and old holes must be covered. This would be quite laborious and not very secure if the old holes were simply patched up with plastic wood or some other weak filler material. A more suitable solution is to use either a wrap around/mag plate or remodeler plates.
Wrap around plates are a continuous piece of steel that wraps around the door and covers all of the holes from the old lock’s preparation. Because of this they are ideal for repairing a door that has been kicked in or is in danger of being kicked in. They are not very aesthetically pleasing though. Remodeler plates also cover all of the holes but use three separate cover plates to do so. They look much nicer but don’t lend the same structural integrity as the wrap around plate.
Installing remodeler plates allows the owner or tenant to replace the locks cheaply when they break or simply want to spare themselves the expense of paying a locksmith to come out and rekey one lock. Tubular locks are available for less than $20 a piece and in the volatile rental market it makes sense to simply install new locks between tenants if you know how. Mortise locks are finicky, allow people to lock themselves out, and sometimes require training to show how to use properly. A landlord who wants to avoid training time and plaintive phone calls at 2 in the morning because of lockouts will want to consider this option.