Can you give me some more information and I'll try to help you.
Is the clock driven by batery, springs or weights?
When you say it doenst keep time, do you mean the hands don't move at all, or that it loses/gains each day?
Have you tried changing the batteries? The pendulum is nothing to do with the timekeeping on these clocks and will often keep going when the batteries are too low to run the clock. Erratic chimes would suggest the same problem.
If this doesn't solve it, you'll need to replace the movement. They're not repairable.
I can give you information on how to find a replacement if you need it.
OK. I believe most Howard Miller clocks use Hermle movements, which are very good quality (so not cheap...). You should be able to see a model number on the back of the movement. It's most likely something like #2214 if it's a Hermle.
There are two places I'd suggest you look for replacements, both do mail order: http://www.clockworks.com/ http://www.timesavers.com/catalog/index.htm
If it is a Hermle movement, clockworks has them on this page:
http://www.clockworks.com/hermlequartz.html along with instructions on how to select the right one.
If it isn't Hermle then it's probably Asian. Timesavers have a bigger selection of these in their catalogue. Either way you also have to measure the length of the spindle that the hands fit on, so you'll probably need to take the old movement out in order to do this.
Hope this answers your question.