You can work without restrictions on a partial old-age pension
You are free to work on a partial old-age pension. Your earnings will not affect the amount of pension you receive.
The pension accrued for the work you have done during partial old-age pension will be granted to you when you retire on old-age pension. In this case, you will have to terminate your employment. If you have several continuous employment relationships, the main employment relationship must end when you retire.