Very common problem. There was a recall to address it for 98s.
A dealer can check your VIN against a national database to
see if the recall was done to your vehicle.

Recall - Front Signal Bulb and Socket Replacement
S70/V70/V70 XC 1998-2000
C70 1998-2001

Section
3

Group
35

No.
0012

Year
01

Month
03

Recall No. 101
Front turn signal bulb and socket, replacement

Background:

In all model year 1998-2000 S/V/C 70s and certain model year 2001 C70s, there may be inadequate contact between the front turn signal bulbs and sockets. In all affected vehicles corrective action consists of replacement of the front turn signal bulbs and sockets with a modified design.