I'm thinking that most clocks are overdue servicing may be the issue with mine. Runs slow, very slow. I've been playing with old clocks and pocket watches for a longish time (less so, well, not at all now die to eyesight, patience and ironically, lack of spare time). The original oil they were lubricated with is often the problem, it's dried out, and combined with some dirt, causes drag. WD40 prob won't help in long run in that case. Strip, clean, check all shafts and bearings, sparingly re-oil with correct clock oil. It's a lot of work, and there may be wear needing replacement parts, and watchmakers who do this are getting thin on ground. I wouldn't bother with mine as it's a major faff and I've only done this a couple of times, and only once successfully! A real skill. But if you know a friendly watch or clock servicers, they would be the people. Apologies if this has already been discussed previously.