undermaintain means to maintain inadequately; to allow to fall into disrepair. Lexicurio rates it Rare gem — a strength score of 83 out of 100.
Etymology
From under- + maintain.
verb
- To maintain inadequately; to allow to fall into disrepair.“For some years locomotives and coaches have been overworked and undermaintained to a degree without precedent in British railway history, and the leeway in maintenance now to be made up is very great.”