In the race for three open seats on the Grass Valley City Council, challenger Jim Firth is leading the pack in campaign funds. Firth, chairman of the Nevada County Democratic Central Committee with three decades of experience as a union negotiator, has brought in $5,529 over the course of the election thus far — $4,000 more than any other candidate, according to campaign finance disclosure documents filed Thursday. Of that amount, Firth has spent $4,177, giving him a balance of $1,352 heading into the last leg of the campaign, which almost matches the total funds raised of the second largest campaign …