I can give you the theory, but what has happened in reality I have no idea.  your residence permit, plus your work permit and your FEC are all tied up with your employer.  In theory, if your contract expires, so does your permits and FEC.  And makes no difference on the expiration date, the one you have may still show validity, but at the computers at Immigration it could be canceled.

Did you get a release letter from your previous employer ?.   Again, in theory once your contract expires, you have 10 days to petition a change on the permits to show the new employer.  If you do not do that, PSB will give you 30 days to leave the country.

All of the above is theory, again what has happened only God knows.

ok thanks for your answer

i have done this twice... i did start the process of applying new visa within 10 days... but both cases it took 3-4 months for getting the new residence permit.. old one was not expired till that date..

I dont know about FEC...  i hold Work Permit (not teacher).. no proof.. but as i understand work permit cancellation will not automatically trigger residence permit cancellation... even my present residence permit expires 4 months past the expiry date of present work permit... 

yea my similar to yours

whats the difference between work permit fec and residence permit arent they tied toegether

and your switch was done fine convert without the need for a new one