There are a couple of things that should be done in order to make sure that your mechanical product functions properly.
You should make sure that your chassis is clean from any dirst especially sand and dust. This is esecially important near the wheels, braking systems, suspension and other moving parts and mechanisms.
Once in a while, it is a good idea to put some grease on wheels axles (if possible) and other parts where friction occurs.
You should not keep your chassis outside especially on rainy days. Should the chassis be wet, we suggest to remove and water from metallic elements.
Put it this way, a stroller can be treated as a bicycle, it is a mechanical product that needs to be properly maintainted in order to assure its best functionality ;)