Vacuum Cleaners Discussions

Hello,
I have an old Montgomery Ward's Signature canister vacuum, model SP-316A, 9.7 Amp's.  It still works, I have all the attachments, and the motor is quite strong.  It is still in good condition.  I can easily lift a basketball with it.

However, it now has a problem with the 20 foot power cord which is pulled out of the canister and is returned into the canister when finished.  When the power cord is pulled out and stopped, I must hit the canister in the back or side to get the electrical contact inside to engage, otherwise the motor will not work.  The rear of the canister is held on by 3 Philips screws.  If I were to pull out the power cord and remove the 3 screws, would I be able to pull out the rear of the unit and at least clean and oil whatever electrical contacts are there?

Because of its age, the unit is really not worth taking to a repairman.  If I cannot repair the unit myself, I'm pretty much stuck with it the way it is or buying another unit.