The original storage cell in Seiko Kinetic movements was I believe a capacitor, the new replacement cells are a lithium polymer rechargeable battery.
The new batteries have a much higher capacity than the original capacitors which has two consequences, the first of which is that from fully charged it can last months of static storage before the watch stops, the second of which is that it takes a lot more movement to charge it up and so takes longer to get it out of the 2 second tick zone.
You may need to do an extended period of charging exercise to get enough power into it in the first place but once there you should be fine.
If the problem persists though you may want to check the free running of the rotor as if this gets tight charging efficiency will be impared.