Problem with Topomatic

I have a Topomatic crank type rolling machine. Of late it has developed a problem which seems to be getting worse with time. After filling the tobacco chamber, I rotate the crank handle, and it does not push the tobacco far enough to completely fill the tube all the way to the filter. Sometimes this problem is very slight, but at other times the unfilled area near the filter is as much as 5/16" to 1/4" in size. When this occurs I either have to discard the finished cigarette, or take the time to roll it between my fingers to release the tobacco. The latter is tedious and time consuming to say the least. Does anyone have experience with this type of problem ? And, If so,
what can I do about it ? Thanks in advance for any help or suggestions you may be able to provide.
                Dalton