I don't know LS220 timer, and internet search turns up no legit information.
I suggest 4 possible solutions:
1) If this is a dial timer with segments, and you pull these segments up to set on-off times: work-around for missing segment is to switch am and pm hours. Fresh set of un-used segments exist on opposite side of dial.
2) Add a comment with clear description of timer.
I will check my files against timers that have replaceable trippers
Specific Intermatic and Tork timers have replaceable tripper parts.
Trippers are available on heavy-duty timers that generally cost more.
3) Identify your timer or similar timer on following link, and then add a comment and I will respond.
http://waterheatertimer.org/Woods-timers-and-manuals.html4) If this timer costs $20 or less, Buy another timer since it would be cheaper than ordering off the internet and paying S&H.
Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on timer or any do-it-yourself project.
Fixya is always less expensive than a service call.