Still got the original Brown Boveri star delta timer in there, with the pneumatic delay unit on it as well, though I do suspect that the delay unit has a failed diaphragm by now, the rubber is not going to last forever. Contactor with the contacts burnt off is a common failing on this old range, and the contact replacement kits are long discontinued as well, as they are considered a service part. For the failed 16A 3 phase unit I would recommend using the 25A frame size units, the larger contacts will last longer, and likely the failure would be the actual armature core finally flowing with time till it binds with the case, the original is likely half way there, but the contacts wore out first. Mechanically those contactors will easily do fifty million mechanical cycles, and at full load easily 2 million cycles, though only with a pure resistive load. Big inductive load probably was around the 50 thousand cycle mark when it failed.
If that is a 3 phase motor best thing is to add on an overload relay to the contactor, as that, in addition to overcurrent protection, also gives phase loss protection, in that if one phase disconnects the differential heating on the other 2 phases will trip the overload out, and for this you probably want it to be manual reset as well.